Thanks. Searching on "Nutty Nutcracker" does turn up some interesting results. Most don't have any photos, much less video, so it's hard to tell if this could be from any of them. A lot of them seem to be much broader comedy than this somewhat subtle one.
The descriptions of PNB's Nutty sound the closest, in part because it's just the last performance of their Nutcracker with some alterations. The part in the clip would have been a perfectly fine Arabian even without the comedy spicing it up. I could well believe the elephant and tiger costumes being Sendak. But knowing nothing more about their production, I can't tell if there's even any resemblance.
I'm thinking now that the Youtube video was perhaps taken from a clip shown on TV ... well, OK, it doesn't take a lot of brilliance to come up with that. But the fact that it starts part way through the movement could mean that someone saw the beginning on TV, said oh this is good, and turned on the recorder.
Thanks again, even if nothing else shows up. At least I'm not the only one wondering ...