4 channel of MPEG2 video at one time (Score 2, Informative)

You can get 2 ReelTime-4 MPEG2 decoder cards in your PC and get 8 channels of video at a time. These cards are made by Visual Circuits http://www.visualcircuits.com/ and they are pretty good, I used them myself. That would solve your problem of having full motion video on 8 screens. Drivers are made only for Win 2K which is donwside, but overall it is very good product if you only need video streaming.