I saw a short thing a few months back about making the last Phish album that was pretty cool.
Had some footage of them talking stuff out with Mitch Froom and some good jamming.
Their drum room has a pair of van doors behind it. it's how the drummer gets in the little dome they built over his kit.
Also "Anthem To Beauty" about the making of Anthem of the Sun, Workingman's Dead, and American Beauty by the Dead.
Check out Lesh's "Searching for The Sound" too, his autobiography. Lot's of stories about studio stuff back then. Great one about TC putting a child's toy spinning top on a grand piano and Dave Hassinger running out of the control room into the live room to see WTF was being done to his piano!