Does anyone else remember Rainbow?

I was having a nostalgic browse through old kids TV shows on Youtube today (inspired by Flea's mention of The Electric Company). And then I googled Rainbow.

Did everyone but me already know about this episode? It shows Zippy, George and Bungle in a whole new light...



(Supposedly it was an episode the cast and crew made as a private joke, but that then escaped and made its way onto the (adult, thankfully) air.)