The 3/1 Unprofessional Friday video cannot be played on the Xbox 360. Tested the HD version, which fails with an error message immediately, and the High version, which plays for several minutes before causing an error message.
This has happened once before, with whichever Unprofessional Friday video was delayed for a couple days because it came in over 5 GB and had to be shrunk using some kind of arcane videographer voodoo. (I forget the exact date, sorry.) Both the HD and High versions failed that time, too.
Every other video I've watched (always the HD version) has worked without problems with the Xbox 360's H.264 decoder. (Jar Times, TNTs, other UPF episodes, Random PC Games, etc.)