PBS's History Detectives has an episode titled Dylan Goes Electric, Beatles Autograph & Frank Zappa Collage. It's interesting stuff, and you may learn a thing or two about Frank that you didn't know.
Tag: Frank Zappa
Wazoo Interview, '74
A Rendezvouz [sic] With The Grand Wazoo, by John David Kalodner, Concert, 1974. Zappa discusses the change from the '60's to the '70's, the changes in the band, and the difference between studios and orchestra halls. Via afka.net.
Envelopes and Little House I Used to Live In on Piano
Via uploader YourArf:
Recorded ca. 1978. Played by Peter Wolf or Tommy Mars (my guess is the latter).
Stories from Vai
Vai has some technical difficulties; uploader thefinestmusic prompts him for some stories about Frank.
Young and Monde
AKA Let's Move to Cleveland. Köln, Germany, 1982 (and if he did Duke of Prunes at that show I could make a "Duke of Köln" joke); uploaded by Steve Sparx.
Ride My Face to Chicago
Uploaded by dragojlodudic.
Speedfreak Boogie
Via tomtiddler1, who says it's from a 1975 broadcast called An Evening With Frank Zappa & Captain Beefheart.
Sleep Dirt
Vancouver, 1975; uploaded by Luff2808. Not sure why the video keeps going for 40 more seconds after the audio cuts out, but here it is anyway.
Panty Rap/Magic Fingers/Flakes
Via tomtiddler1. Santa Monica, 1980.
Channel 68 Interview, Part 3
Rounding it off.
Uploader koolstrike notes that he had to remove a couple of song cuts for copyright reasons, but the interview itself is intact.