Running Down a Dream, directed by Peter Bogdanovich. Tied with Sparks Brothers as my favourite music documentary.
you forgot Spinal Tap...
Ha, that is, if you will, a rockumentary.
Spinal Tap is in the same zone as The Rutles imho, not really a "documentary", or indeed a fake documentary
BTW spinal Tap and The Rutles are my two fav movies in the music territory