First off, I really want to see "Punk:Attitude" but haven't had the opportunity. Glad to hear that it's a good film.
The only "Must See" or "Must Hear" extras I can think of off the top of my head is the "This is Spinal Tap" special edition. There are loads of scenes that didn't make it into the movie (almost a whole other movie's worth), but the commentary by "the band" in character is worth every moment. It's priceless.
These aren't movies, but TV comedy shows from BBC America that you might like (or may already own) that I find hysterically funny. First, "Knowing Me, Knowing You with Alan Partridge" starring Steve Coogan of "24 Hour Party People" fame, and "The Kumars at No. 42". Excellent send-ups of chat shows.