Here's a video clip (mpg file for download) of John Lennon, Eric Clapton, Keith Richards and Mitch Mitchell (Jimi Hendrix Experience) performing under the name Dirty Mac as part of the Rolling Stone's 1968 TV special, Rock and Roll Circus.
After an unfunny Mick Jagger (doing a lame American accent) interviews an amusing John Lennon, the impromptu supergroup launches into a version of Yer Blues that makes the White Album version sound lame and hollow. This was the first time Beatle John had performed in public without The Beatles, and fortunately audio and video were on hand to preserve a great performance, with Keith on bass, Clapton on guitar, Mitchell on drums and Yoko mercifully crawling into an un-mic'ed black elastic bag. Apparently on other songs that day, Yoko provided her customary caterwauling. (If it's Yoko caterwauling on TV behind Lennon you want, see The Professor's post about the Mike Douglas show performance that made Chuck Berry's eyes roll.