I have a love/hate thing with rock docs because most of them are pure hagiography but here's 5 that haven't been mentioned (I skim-read) so far
FRIENDS FOREVER - who are Friends Forever? They're a duo who are more performance art than band. They play in their van parked outside the venue they're booked at. They live in the van, with their dog, and occasionally a girlfriend. They are all complete space cadets who hate the idea of any commerce (ie. trying to break even) let alone make money. They drive all the way to New York to play one song for the people at Troma Studios and then the head of Troma meets them and forgets their name. It is a snapshot of a world that no longer exists.
GIMME SHELTER - I am not Stones fan but this is really superior piece. The first half that intersperses the setting up of Altamont with some concert footage is fine, but the second half is a masterclass in editing together the sense of an impending disaster as thousands of drug casualties are martialled by violent psychopaths to let a rock band congratulate itself for being successful. A rare example of The Grateful Dead having a good idea when they split without playing.
DIG! - did anyone say Dig!? If not shame on you. The intertwining fates of The Brian Jonestown Massacre and The Dandy Warhols as the former trudge through disasters to pursue a singular vision while the latter leech off them and become famous, causing jealousy and rage and revenge. When I first saw this I didn't realise BJM are meant to be good, but now I like them a little more the film hits different. Some incredible scenes (sitar-breakage, the wuss who forms Black Rebel Motorcycle Club walking out of the tour) and fair play to the Warhols guy for narrating it.
there are two films I am recommending and I can't even remember the titles [EDIT = remembered one!]
OFF THE CHARTS - THE SONG-POEM STORY - THIS is a film I saw at the Slint ATP on the channel programmed by the band member who had a video shop. It was about these session musicians who record songs based around lyrics that people send in to them (they take out adverts in the paper). Just a great weird insight into a fringe business where these could-have-been pros are singing mental lyrics about someone's cat.
the other one - this barely constitutes a recommendation as I can't even remember the name of the band - is about a terrible band from somewhere in the Midwest doing one last tour. They are sort of liked in their mid-sized cultural desert town but as soon as they leave its postcode they are nothing. They book these gigs that literally no one cares about and they all sort of realise, in a frustrated and bitter way, that they're not going to make it, culminating in a self-revelation at a pathetic gig in a branch of Hot Topic.
BONUS
SLOW CENTURY - Pavement documentary is only minimally revelatory but the commentaries on the videos are very funny.