5 minutes (We Are The Champions). Broadcasted on TV. An uncut recording apparently exists.
Video - downloads
pre-show footage: linkmediafire (TV report only): link
Line-up
Freddie Mercury (lead vocals, piano, electric guitar),
Brian May (electric guitar, backing vocals, acoustic guitar, keyboards),
Roger Taylor (drums, backing vocals, tambourine),
John Deacon (bass guitar),
Spike Edney (keyboards, piano, electric guitar, backing vocals),
Fish (vocals in Tutti Frutti)