well you can apply videos as textures to objects, but if you try to export to vrml the video won't play - animation isn't exported, only models and textures. (baked lighting) the video would be an animated texture so you might only get the first frame of each.

if you rendered it out the video would play... but don't render out to an avi file, render to an image sequence - and then put it together in final cut.

i know in adobe after effects you can move the 'camera' and video layers around in 3d space, but i haven't actually played with it yet.

edit: as far as 'actual projection' like you were talking about, you might be able to map the videos to the color portion of a spotlight and then actually project it like as from a film projector... so if objects get in the way the light would be cast on the objects and not on the screen...