Then, all you'd have to do is set that BG to the room BG and keep replacing it every step. You can play with sprites, etc on top of it, and you'd never have to worry about the player right-clicking and getting all those options, and you'd have full control over your display of the movie.
You know, something even neater would be if you could make buttons and thingies in GM and have them on top of the video and you could even interactively play a game on top of a video, kind of how they do in Final Fantasy 7 and 8.
Just food for thought...











