What about "High Fidelity"--if you're talking rock culture in the broad sense, it certainly applies. And Jack Black's performance clip makes it qualify in the more specific sense.
If you're thinking proto-punk or pre-New Wave, see about getting the Warhol Velvet Underground and Nico short. Plus there are videos of the Lou Reed American Masters doc, the Lou Reed/John Cale "Songs for Drella" and a great doc on Nico called "Nico/Icon" by Susanne Ofteringer. (I know you said you don't need any more input on documentaries but these may be overlooked.)
Greg Callahan