add SetPlayback to tastudio lua library. Can't be 100% sure it works, but it seems to be working OK. it may hang everything up if you seek through a really long redzone.....

BizHawk.Client.Common/movie/tasproj/TasMovieMarker.cs

@@ -282,6 +282,11 @@ namespace BizHawk.Client.Common
 				.FirstOrDefault();
 		}
 
+		public int FindIndex(string markerName)
+		{
+			return this.FindIndex(m => m.Message == markerName);
+		}
+
 		public bool IsMarker(int frame)
 		{
 			return this.Any(m => m == frame);

BizHawk.Client.EmuHawk/tools/Lua/Libraries/EmuLuaLibrary.Tastudio.cs

@@ -155,6 +155,30 @@ namespace BizHawk.Client.EmuHawk
 			return false;
 		}
 
+		[LuaMethodAttributes(
+			"setplayback",
+			"Seeks the given frame (a number) or marker (a string)"
+		)]
+		public void SetPlayback(object frame)
+		{
+			if (Engaged())
+			{
+				int f;
+				if (frame is double) f = (int)(double)frame;
+				else
+				{
+					//r marker = Tastudio.CurrentTasMovie.Markers.Get(frame);
+					f = Tastudio.CurrentTasMovie.Markers.FindIndex((string)frame);
+					if (f == -1) return;
+					f = Tastudio.CurrentTasMovie.Markers[f].Frame;
+				}
+				if (f < Tastudio.CurrentTasMovie.InputLogLength && f>=0)
+				{
+					Tastudio.GoToFrame(f);
+				}
+			}
+		}
+
 		[LuaMethodAttributes(
 			"onqueryitembg",
 			"called during the background draw event of the tastudio listview"