I believe Halfer found it in assembly - there is FPS limiter indeed in the game. Switching it off makes the game act like speed booster on Steam version. There are two movie playing functions in engine, every single points to core movie playing algorithm, that every time disables the FPS lock, therefore anytime movie is played, the fps limit is dropped and as soon as the movie ends, the frame limiter is again set. Forcing frame limiter on movie makes it go with normal speed, but displays only 1/2 of frames. It's like a frame skipping on movie. The frame limiter variable is operated only from movie playing sub-functions [or at least IDA shows it so]
I have never tested it personally, but the game should display any FPS movie.