[3] 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 performed as part of a one-shot supergroup called The Dirty Mac, featuring Eric Clapton on guitar, Mitch Mitchell (of The Jimi Hendrix Experience) on drums, and the Stones' Keith Richards on bass.

[4] (As the Who's Pete Townshend recalled, an earlier idea for a circus-themed concert tour had been floated; it would have featured the Stones, the Who, and the Small Faces.

The project was conceived by Mick Jagger as a way to promote the Stones' album Beggars Banquet beside conventional press and concert appearances.

[12] Of the Dirty Mac's one-song, one-off performance, the journalist David Dalton, who attended the filming, wrote in Rolling Stone magazine in 1970, "Simply the presence of all these magicians together is completely overwhelming."

After the group's performance of Lennon's "Yer Blues," which segued into an extended, avant-garde jam featuring Ono's wailing, Dalton described the audience as "totally awestruck; they do not move or talk.

Some of the footage of the concert was thought to be lost or destroyed until 1993, when it was discovered in a bin in the Who's private film vault by the director/producer team Michael Gochanour and Robin Klein.

A significant segment, of the Who performing "A Quick One", had been shown theatrically in the documentary The Kids Are Alright (1979), the only public viewing of the film until its eventual release.

This concert is the only footage of Black Sabbath guitarist Tony Iommi performing as a member of Jethro Tull, during his brief two-week tenure as a replacement for Mick Abrahams.

The Rolling Stones forced them to cut their rehearsal time short, although Ian Anderson sings and plays flute live on "A Song For Jeffrey."

Of particular interest in the Townshend interview is his description of the genesis of the Circus project, which he claims was initially meant to involve the performers travelling across the United States via train (a concept used for a short concert series in Canada that was later documented in the feature film Festival Express).

The remastered DVD also includes a special four-camera view of The Dirty Mac's performance of The Beatles' "Yer Blues" (showing Yoko Ono kneeling on the floor in front of the musicians, completely covered in a black sheet).