diff --git a/src/BizHawk.Client.Common/movie/MovieConversionExtensions.cs b/src/BizHawk.Client.Common/movie/MovieConversionExtensions.cs
index 8ec5bf7fdf..85330e9081 100644
--- a/src/BizHawk.Client.Common/movie/MovieConversionExtensions.cs
+++ b/src/BizHawk.Client.Common/movie/MovieConversionExtensions.cs
@@ -4,17 +4,6 @@ using System.Linq;
 
 using BizHawk.Common;
 using BizHawk.Common.PathExtensions;
-using BizHawk.Emulation.Common;
-using BizHawk.Emulation.Cores.Arcades.MAME;
-using BizHawk.Emulation.Cores.Atari.Jaguar;
-using BizHawk.Emulation.Cores.Consoles.Nintendo.Ares64;
-using BizHawk.Emulation.Cores.Consoles.Nintendo.Gameboy;
-using BizHawk.Emulation.Cores.Consoles.Nintendo.NDS;
-using BizHawk.Emulation.Cores.Consoles.Sega.gpgx;
-using BizHawk.Emulation.Cores.Consoles.Sega.PicoDrive;
-using BizHawk.Emulation.Cores.Nintendo.NES;
-using BizHawk.Emulation.Cores.Nintendo.SubNESHawk;
-using BizHawk.Emulation.Cores.Sega.MasterSystem;
 
 namespace BizHawk.Client.Common
 {
@@ -183,127 +172,6 @@ namespace BizHawk.Client.Common
 			return tas;
 		}
 
-		// TODO: This doesn't really belong here, but not sure where to put it
-		public static void PopulateWithDefaultHeaderValues(
-			this IMovie movie,
-			IEmulator emulator,
-			ISettingsAdapter settable,
-			IGameInfo game,
-			FirmwareManager firmwareManager,
-			string author)
-		{
-			movie.Author = author;
-			movie.EmulatorVersion = VersionInfo.GetEmuVersion();
-			movie.OriginalEmulatorVersion = VersionInfo.GetEmuVersion();
-			movie.SystemID = emulator.SystemId;
-
-			if (settable.HasSyncSettings)
-			{
-				movie.SyncSettingsJson = ConfigService.SaveWithType(settable.GetSyncSettings());
-			}
-
-			movie.GameName = game.FilesystemSafeName();
-			movie.Hash = game.Hash;
-			if (game.FirmwareHash != null)
-			{
-				movie.FirmwareHash = game.FirmwareHash;
-			}
-
-			if (emulator.HasBoardInfo())
-			{
-				movie.BoardName = emulator.AsBoardInfo().BoardName;
-			}
-
-			if (emulator.HasRegions())
-			{
-				var region = emulator.AsRegionable().Region;
-				if (region == DisplayType.PAL)
-				{
-					movie.HeaderEntries.Add(HeaderKeys.Pal, "1");
-				}
-			}
-
-			if (firmwareManager.RecentlyServed.Count != 0)
-			{
-				foreach (var firmware in firmwareManager.RecentlyServed)
-				{
-					var key = firmware.ID.MovieHeaderKey;
-					if (!movie.HeaderEntries.ContainsKey(key))
-					{
-						movie.HeaderEntries.Add(key, firmware.Hash);
-					}
-				}
-			}
-
-			if (emulator is NDS nds && nds.IsDSi)
-			{
-				movie.HeaderEntries.Add("IsDSi", "1");
-
-				if (nds.IsDSiWare)
-				{
-					movie.HeaderEntries.Add("IsDSiWare", "1");
-				}
-			}
-
-			if ((emulator is NES nes && nes.IsVS)
-				|| (emulator is SubNESHawk subnes && subnes.IsVs))
-			{
-				movie.HeaderEntries.Add("IsVS", "1");
-			}
-
-			if (emulator is IGameboyCommon gb)
-			{
-				//TODO doesn't IsCGBDMGMode imply IsCGBMode?
-				if (gb.IsCGBMode) movie.HeaderEntries.Add(gb.IsCGBDMGMode ? "IsCGBDMGMode" : "IsCGBMode", "1");
-			}
-
-			if (emulator is SMS sms)
-			{
-				if (sms.IsSG1000)
-				{
-					movie.HeaderEntries.Add("IsSGMode", "1");
-				}
-
-				if (sms.IsGameGear)
-				{
-					movie.HeaderEntries.Add("IsGGMode", "1");
-				}
-			}
-
-			if (emulator is GPGX gpgx && gpgx.IsMegaCD)
-			{
-				movie.HeaderEntries.Add("IsSegaCDMode", "1");
-			}
-
-			if (emulator is PicoDrive pico && pico.Is32XActive)
-			{
-				movie.HeaderEntries.Add("Is32X", "1");
-			}
-
-			if (emulator is VirtualJaguar jag && jag.IsJaguarCD)
-			{
-				movie.HeaderEntries.Add("IsJaguarCD", "1");
-			}
-
-			if (emulator is Ares64 ares && ares.IsDD)
-			{
-				movie.HeaderEntries.Add("IsDD", "1");
-			}
-
-			if (emulator is MAME mame)
-			{
-				movie.HeaderEntries.Add(HeaderKeys.VsyncAttoseconds, mame.VsyncAttoseconds.ToString());
-			}
-
-			if (emulator.HasCycleTiming())
-			{
-				movie.HeaderEntries.Add(HeaderKeys.CycleCount, "0");
-				movie.HeaderEntries.Add(HeaderKeys.ClockRate, "0");
-			}
-
-			movie.Core = emulator.Attributes().CoreName;
-		}
-
 		internal static string ConvertFileNameToTasMovie(string oldFileName)
 		{
 			if (oldFileName is null) return null;
diff --git a/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs b/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs
index d2ba2bd5ed..fec81f1e89 100644
--- a/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs
+++ b/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs
@@ -17,6 +17,7 @@ namespace BizHawk.Client.EmuHawk
 		bool EmulatorPaused { get; }
 
 		/// <remarks>only referenced from <see cref="TAStudio"/></remarks>
+		// TODO: remove? or does anything ever need access to the FirmwareManager
 		FirmwareManager FirmwareManager { get; }
 
 		/// <remarks>only referenced from <see cref="TAStudio"/></remarks>
@@ -81,7 +82,7 @@ namespace BizHawk.Client.EmuHawk
 
 		void SetMainformMovieInfo();
 
-		bool StartNewMovie(IMovie movie, bool record);
+		bool StartNewMovie(IMovie movie, bool newMovie);
 
 		/// <remarks>only referenced from <see cref="BasicBot"/></remarks>
 		void Throttle();
diff --git a/src/BizHawk.Client.EmuHawk/MainForm.Events.cs b/src/BizHawk.Client.EmuHawk/MainForm.Events.cs
index 5fb9121a17..5bea05ba63 100644
--- a/src/BizHawk.Client.EmuHawk/MainForm.Events.cs
+++ b/src/BizHawk.Client.EmuHawk/MainForm.Events.cs
@@ -173,10 +173,6 @@ namespace BizHawk.Client.EmuHawk
 				= RecentMovieSubMenu.Enabled
 					= !Emulator.IsNull() && !Tools.IsLoaded<TAStudio>();
 
-			// Record movie dialog should not be opened while in need of a reboot,
-			// Otherwise the wrong sync settings could be set for the recording movie and cause crashes
-			RecordMovieMenuItem.Enabled &= !RebootStatusBarIcon.Visible;
-
 			PlayFromBeginningMenuItem.Enabled = MovieSession.Movie.IsActive() && !Tools.IsLoaded<TAStudio>();
 		}
 
@@ -368,7 +364,7 @@ namespace BizHawk.Client.EmuHawk
 			// Nag user to user a more accurate core, but let them continue anyway
 			EnsureCoreIsAccurate();
 
-			using var form = new RecordMovie(this, Config, Game, Emulator, MovieSession, FirmwareManager);
+			using var form = new RecordMovie(this, Config, Game, Emulator, MovieSession);
 			this.ShowDialogWithTempMute(form);
 		}
 
diff --git a/src/BizHawk.Client.EmuHawk/MainForm.Movie.cs b/src/BizHawk.Client.EmuHawk/MainForm.Movie.cs
index a4e8564e7b..e3bbcd687d 100644
--- a/src/BizHawk.Client.EmuHawk/MainForm.Movie.cs
+++ b/src/BizHawk.Client.EmuHawk/MainForm.Movie.cs
@@ -2,13 +2,24 @@ using System.Collections.Generic;
 using System.Windows.Forms;
 
 using BizHawk.Client.Common;
+using BizHawk.Common;
 using BizHawk.Emulation.Common;
+using BizHawk.Emulation.Cores.Arcades.MAME;
+using BizHawk.Emulation.Cores.Atari.Jaguar;
+using BizHawk.Emulation.Cores.Consoles.Nintendo.Ares64;
+using BizHawk.Emulation.Cores.Consoles.Nintendo.Gameboy;
+using BizHawk.Emulation.Cores.Consoles.Nintendo.NDS;
+using BizHawk.Emulation.Cores.Consoles.Sega.gpgx;
+using BizHawk.Emulation.Cores.Consoles.Sega.PicoDrive;
+using BizHawk.Emulation.Cores.Nintendo.NES;
+using BizHawk.Emulation.Cores.Nintendo.SubNESHawk;
+using BizHawk.Emulation.Cores.Sega.MasterSystem;
 
 namespace BizHawk.Client.EmuHawk
 {
 	public partial class MainForm
 	{
-		public bool StartNewMovie(IMovie movie, bool record)
+		public bool StartNewMovie(IMovie movie, bool newMovie)
 		{
 			if (movie is null) throw new ArgumentNullException(paramName: nameof(movie));
 
@@ -24,6 +35,7 @@ namespace BizHawk.Client.EmuHawk
 			var oldPreferredCores = new Dictionary<string, string>(Config.PreferredCores);
 			try
 			{
+				if (newMovie) PrepopulateMovieHeaderValues(movie);
 				try
 				{
 					MovieSession.QueueNewMovie(
@@ -48,7 +60,13 @@ namespace BizHawk.Client.EmuHawk
 
 				Config.RecentMovies.Add(movie.Filename);
 
-				MovieSession.RunQueuedMovie(record, Emulator);
+				MovieSession.RunQueuedMovie(newMovie, Emulator);
+				if (newMovie)
+				{
+					PopulateWithDefaultHeaderValues(movie);
+					if (movie is ITasMovie tasMovie)
+						tasMovie.ClearChanges();
+				}
 			}
 			finally
 			{
@@ -138,5 +156,132 @@ namespace BizHawk.Client.EmuHawk
 				}
 			}
 		}
+
+		/// <summary>
+		/// Sets necessary movie values in order to be able to start this <paramref name="movie"/>
+		/// Only required when creating a new movie from scratch.
+		/// </summary>
+		/// <param name="movie">The movie to fill with values</param>
+		private void PrepopulateMovieHeaderValues(IMovie movie)
+		{
+			movie.Core = Emulator.Attributes().CoreName;
+			movie.SystemID = Emulator.SystemId; // TODO: I feel like setting this shouldn't be necessary, but it is currently
+
+			var settable = GetSettingsAdapterForLoadedCoreUntyped();
+			if (settable.HasSyncSettings)
+			{
+				movie.SyncSettingsJson = ConfigService.SaveWithType(settable.GetSyncSettings());
+			}
+		}
+
+		/// <summary>
+		/// Sets default header values for the given <paramref name="movie"/>. Notably needs to be done after loading the core
+		/// to make sure all values are in the correct state, see https://github.com/TASEmulators/BizHawk/issues/3980
+		/// </summary>
+		/// <param name="movie">The movie to fill with values</param>
+		private void PopulateWithDefaultHeaderValues(IMovie movie)
+		{
+			movie.EmulatorVersion = VersionInfo.GetEmuVersion();
+			movie.OriginalEmulatorVersion = VersionInfo.GetEmuVersion();
+
+			movie.GameName = Game.FilesystemSafeName();
+			movie.Hash = Game.Hash;
+			if (Game.FirmwareHash != null)
+			{
+				movie.FirmwareHash = Game.FirmwareHash;
+			}
+
+			if (Emulator.HasBoardInfo())
+			{
+				movie.BoardName = Emulator.AsBoardInfo().BoardName;
+			}
+
+			if (Emulator.HasRegions())
+			{
+				var region = Emulator.AsRegionable().Region;
+				if (region == DisplayType.PAL)
+				{
+					movie.HeaderEntries.Add(HeaderKeys.Pal, "1");
+				}
+			}
+
+			if (FirmwareManager.RecentlyServed.Count != 0)
+			{
+				foreach (var firmware in FirmwareManager.RecentlyServed)
+				{
+					var key = firmware.ID.MovieHeaderKey;
+					if (!movie.HeaderEntries.ContainsKey(key))
+					{
+						movie.HeaderEntries.Add(key, firmware.Hash);
+					}
+				}
+			}
+
+			if (Emulator is NDS nds && nds.IsDSi)
+			{
+				movie.HeaderEntries.Add("IsDSi", "1");
+
+				if (nds.IsDSiWare)
+				{
+					movie.HeaderEntries.Add("IsDSiWare", "1");
+				}
+			}
+
+			if ((Emulator is NES nes && nes.IsVS)
+				|| (Emulator is SubNESHawk subnes && subnes.IsVs))
+			{
+				movie.HeaderEntries.Add("IsVS", "1");
+			}
+
+			if (Emulator is IGameboyCommon gb)
+			{
+				//TODO doesn't IsCGBDMGMode imply IsCGBMode?
+				if (gb.IsCGBMode) movie.HeaderEntries.Add(gb.IsCGBDMGMode ? "IsCGBDMGMode" : "IsCGBMode", "1");
+			}
+
+			if (Emulator is SMS sms)
+			{
+				if (sms.IsSG1000)
+				{
+					movie.HeaderEntries.Add("IsSGMode", "1");
+				}
+
+				if (sms.IsGameGear)
+				{
+					movie.HeaderEntries.Add("IsGGMode", "1");
+				}
+			}
+
+			if (Emulator is GPGX gpgx && gpgx.IsMegaCD)
+			{
+				movie.HeaderEntries.Add("IsSegaCDMode", "1");
+			}
+
+			if (Emulator is PicoDrive pico && pico.Is32XActive)
+			{
+				movie.HeaderEntries.Add("Is32X", "1");
+			}
+
+			if (Emulator is VirtualJaguar jag && jag.IsJaguarCD)
+			{
+				movie.HeaderEntries.Add("IsJaguarCD", "1");
+			}
+
+			if (Emulator is Ares64 ares && ares.IsDD)
+			{
+				movie.HeaderEntries.Add("IsDD", "1");
+			}
+
+			if (Emulator is MAME mame)
+			{
+				movie.HeaderEntries.Add(HeaderKeys.VsyncAttoseconds, mame.VsyncAttoseconds.ToString());
+			}
+
+			if (Emulator.HasCycleTiming())
+			{
+				movie.HeaderEntries.Add(HeaderKeys.CycleCount, "0");
+				movie.HeaderEntries.Add(HeaderKeys.ClockRate, "0");
+			}
+		}
 	}
 }
diff --git a/src/BizHawk.Client.EmuHawk/movie/RecordMovie.cs b/src/BizHawk.Client.EmuHawk/movie/RecordMovie.cs
index 439772bb13..6fcf09c699 100644
--- a/src/BizHawk.Client.EmuHawk/movie/RecordMovie.cs
+++ b/src/BizHawk.Client.EmuHawk/movie/RecordMovie.cs
@@ -24,7 +24,6 @@ namespace BizHawk.Client.EmuHawk
 		private readonly GameInfo _game;
 		private readonly IEmulator _emulator;
 		private readonly IMovieSession _movieSession;
-		private readonly FirmwareManager _firmwareManager;
 
 		private readonly TextBox AuthorBox;
 
@@ -41,8 +40,7 @@ namespace BizHawk.Client.EmuHawk
 			Config config,
 			GameInfo game,
 			IEmulator core,
-			IMovieSession movieSession,
-			FirmwareManager firmwareManager)
+			IMovieSession movieSession)
 		{
 			if (game.IsNullInstance()) throw new InvalidOperationException("how is the traditional Record dialog open with no game loaded? please report this including as much detail as possible");
 
@@ -51,7 +49,6 @@ namespace BizHawk.Client.EmuHawk
 			_game = game;
 			_emulator = core;
 			_movieSession = movieSession;
-			_firmwareManager = firmwareManager;
 
 			SuspendLayout();
 
@@ -222,6 +219,7 @@ namespace BizHawk.Client.EmuHawk
 				}
 
 				var movieToRecord = _movieSession.Get(path);
+				movieToRecord.Author = AuthorBox.Text ?? _config.DefaultAuthor;
 
 				var fileInfo = new FileInfo(path);
 				if (!fileInfo.Exists)
@@ -260,12 +258,6 @@ namespace BizHawk.Client.EmuHawk
 					movieToRecord.SaveRam = core.CloneSaveRam();
 				}
 
-				movieToRecord.PopulateWithDefaultHeaderValues(
-					_emulator,
-					((MainForm) _mainForm).GetSettingsAdapterForLoadedCoreUntyped(), //HACK
-					_game,
-					_firmwareManager,
-					AuthorBox.Text ?? _config.DefaultAuthor);
 				_mainForm.StartNewMovie(movieToRecord, true);
 
 				_config.UseDefaultAuthor = DefaultAuthorCheckBox.Checked;
diff --git a/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs b/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs
index e9773faee5..684d75d523 100644
--- a/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs
+++ b/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs
@@ -580,18 +580,12 @@ namespace BizHawk.Client.EmuHawk
 
 			var filename = DefaultTasProjName(); // TODO don't do this, take over any mainform actions that can crash without a filename
 			var tasMovie = (ITasMovie)MovieSession.Get(filename);
+			tasMovie.Author = Config.DefaultAuthor;
 			tasMovie.BindMarkersToInput = Settings.BindMarkersToInput;
 
 			tasMovie.GreenzoneInvalidated = GreenzoneInvalidated;
 			tasMovie.PropertyChanged += TasMovie_OnPropertyChanged;
 
-			tasMovie.PopulateWithDefaultHeaderValues(
-				Emulator,
-				((MainForm) MainForm).GetSettingsAdapterForLoadedCoreUntyped(), //HACK
-				Game,
-				MainForm.FirmwareManager,
-				Config.DefaultAuthor);
-
 			_ = StartNewMovieWrapper(tasMovie, isNew: true);
 
 			// clear all selections