Is it possible to use analog video output as input?
If your problem is finding a way to send the video to the Pi, you probably need somthing like this: http://www.amazon.com/EasyCAP-DC60-Creator-Capture-High-quality/dp/B002H3BSCM
As for the software to use with it... I guess a throrough search on Google for Linux apps that can fetch analog input from the USB could do the trick.
