here is some info that Evan very kindly provided, the basic concept is very straightforward
"This device uses a very cheap and simple method for modular video synthesis. The camera is hooked up to a composite-to-VGA converter box... This has a VGA cable coming out of it, which I slit open to get at the individual conductors inside. This gives you access to the red, green and blue video signal channels on separate lines, as well as the HSYNC and VSYNC signals."
VGA video synthesizer test 2 from Evan Montpellier on Vimeo.