Here are a few that come quickly to mind:
"It Might Get Loud". Jack White, Jimmy Page, The Edge, and three very different approaches to playing rock guitar.
My brother says " Summer of Soul" about the 'black Woodstock' is worth a watch.
The long delayed "Amazing Grace" with Aretha Franklin is a good companion to the album. Lots of fun picking out the celebrities in the audience. More of a concert film than a documentary, though.
Peter Jackson's "Get Back" runs 8 hours in three parts, each of which has its own emotional arc. Worth it, worth it, worth it.
"Long Strange Trip" touches on all things Grateful Dead in four hours across several episodes.
"Hail Hail, Rock and Roll" pits Keith Richards against Chuck Berry as they stage a pair of shows in St Louis - an old film, but it holds up. Spoiler alert: Chuck wins.
Another all star tribute show worth a watch is "Black and White Night" with Roy Orbison backed by an A list of rock musicians.
"1,000 Years of Popular Music" is another concert film, not a documentary. Richard Thompson took Playboy's writing prompt to list the best pop tunes in the last Millennium literally. He starts with a quick and cheerful Renaissance drinking song and ends with perhaps the most sinister cover of "Oops I Did it Again!" ever recorded.
And the episodes of "Classic Albums" are pretty good. "Anthem to Beauty" is one of my favorites, but there are interesting things in all of these.
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