Did you ever try to copy a film with a video camera? It is so difficult in the dark to operate the camera and the projector; the controls on each face each other! A rear projection screen makes the job much easier. The projector and the camera are at right angles. You sit between both controls. Easy. I saw one at a flea market and just had to get it for some frustrated film/video maker to use. So I put it up on e-bay for you. I also have one of my own to use and don't need another; image area is about 5x7.
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1946635507