This is probably old hat to anybody who has worked with video for a long time but to me, about a week in, it's extremely cool.

Basically, if you put luma keys on both channels, turn one up all the way, and flick the other between about 75% and 100%, the video in the "flicked channel" starts feeding back on itself.

You can create "motion blur" effects and "freeze" effects, and it gets even crazier if you combine it with other effects. (Now I know how they did a lot of the old school "TV graphics".)

Not something I'd do all the time, but there are whole universes of cool stuff to explore in this. Makes me want to write up some R,G, and B Chroma Key effects to compliment the Luma Key.

I'd write a video feedback effect to attain this on one deck only, but I'm not sure if shaders can feedback on themselves, since it would require memory of the previous frame.

rs