This wonderful bit of hand-made equipment is from "Gieskes"*—he calls it the "Camera Sequencer" and uses it to "make visuals with [his] gameboy music concerts." When you first start watching the video it might not make sense—it didn't to me—but skip to the last third of the video to see the results of the contraption. The contrast between the low-bit music of the Gameboy with the completely mechanical visuals is really nice.
Project Page [Gieskes.nl via Regine/WMMNA]
* I hope I'm getting his name right!