The Circus film is my favourite film of the Stones at their best.
It was filmed in December 1968, the same month the band released Beggars Banquet, the first in a long line of top quality albums, as opposed to their earlier, poppy albums.
Also playing at the Circus was Jethro Tull, The Who, Taj Mahal, John Lennon (with Yoko and Eric Clapton), Marianne Faithfull and of course, The Rolling Stones.
This was filmed about 6 or 7 months before Brian died, and arguably, he definitely looks worn out. (And to any British viewers, don't you think his hairstyle here slightly resembles Pauline Fowler's from EastEnders??)