Fucking finally, an official copy of this amazing footage on YouTube. (As of six days ago!) No more take-downs.
According to the sometimes-reliable Wikipedia …
The Rolling Stones Rock and Roll Circus was a concert show organised by the Rolling Stones on 11 December 1968. The show was filmed on a makeshift circus stage with Jethro Tull, the Who, Taj Mahal, Marianne Faithfull, and the Rolling Stones. John Lennon and his fiancee Yoko Ono also performed as part of a one-shot supergroup called the Dirty Mac, featuring Eric Clapton, Mitch Mitchell, and Keith Richards … It was meant to be aired on the BBC, but instead the Rolling Stones withheld it. The Rolling Stones contended they did so because of their substandard performance, clearly exhausted after 15 hours (and some indulgence in drugs) … Some speculate that another reason for not releasing the film was that the Who, who were fresh off a concert tour, seemingly upstaged the Stones on their own production.
Eventually released in 1996. Enjoy or don’t, you dirty bastards.