You can try vade's movieloader. Download at: http://v002.info/?page_id=13
Just put the .plugin file into /Library/Graphics/Quartz Composer Patches
Start Quartz Composer and
Drag v002movieplayer from the Patch Creator into your composition.
Drag a billboard into the composition.
Connect the Image from the v002movieplayer to the Image from the Billboard
Doubleclick on the Movie Path in the v002 Movie Player and drop your movie into the path.
The v002movieplayer Plugin plays the movies in a smoother way and with more controls over the video than Quartz Composers own movieplayer.