Wonder if it's this guy's work: https://en.wikipedia.org/wiki/Paul_Robertson_(animator)

It is: http://probertson.tumblr.com/image/149391046309

Slightly disappointingly it's just a big 1.4MB file with 32 frames in it...

I wonder if if could be done two orders of magnitude smaller with old-school 8-bit demoscene colour palette cycling? That's clearly the aesthetic they're referencing... I bet some early '90's graphics hacker could have made that in 4096 bytes ;-) (probably not - certainly not at the full 700+ x 500+ resolution...)

The color cycling images I've seen have all been static. How would it work when there's this much animation involved?

It wouldn't

It actually would! Someone posted this on HN recently: http://www.effectgames.com/demos/canvascycle/?sound=0

They are all static.

Maybe it would work if you can color cycle a gif, and keep the animated parts solid colors and cycle the background.

I have seen that before, but I don't think the level of complexity in the BlackBox gif would be achievable with that technique (assuming the technical constraints did also apply)