Anyway... just for the record, the xwinwrap possibility let me curious and i tried it, compiled for the N900 and tried it with mplayer. It didn't work. It did indeed show the mplayer movie on the screen, but no UI elements and I wasn't able to interact with it either. I used "power" and "Ctrl-backspace" to get back the UI but then the video was not showing in the background (the sound was working and the mplayer text showed it running, though).