I want to have video playing as a 2D background except for when I have a 3D object in front of it, the video bends and warps on the object. Just as if someone stood in the way of a video projector. I can't figure this out. Thanks
Try and see if a displacement map would work. Place your 2d projection on the top, 3d object below, and have it cross. Add a displacement map to the video feed (which should be on a screen or lighten mode) and then point the 3d object (or a precomp of the object) to be the displacement map, then adjust the displacement properties. Voala.