sorta thing coulda been in MIMMs' books, Boy's Life, Popular Electronics, etc... Hard to goog, though.
Heh, wire up Hue and Sat, and a tiny bit more circuitry on Value/Intensity, and yah got a shadow-puppet blue/green-screen from the DVD!
Ah, CRT only... duh. *maybe* STN LCDs.
Also, record in realtime with yer vcr ;)
Apparently, there is a scanner made from picture tubes [rather'n camera tubes] "Flying Spot Scanner" [see wikipedia].