Well. I've made some progress.
Messing around with the DirectSound acceleration, the DirectDraw acceleration and software mode, I got cutscenes in Residual to work sometimes (although I'm not sure what the settings are now, since now they seem to have stopped working).
On the other hand, in ScummRev5, when I stand on an SNM file inside a movie LAB, it lets me 'save decompressed zlib file'. This file can be played in the X-Wing Alliance cutscene player
, from here
Unfortunately the program only supports the extraction of individual frames, and has no frame by frame playback. Trying to capture the video directly from the screen still gives poor results.
Would there be any point in decompressing all the files and putting them back into a LAB file, so that either Grim itself or Residual takes up less resources playing them, thus making the capture less jerky?
Is there perhaps some way to expand on that player?