Ono was a sometime member of Fluxus, a loose association of Dada-inspired avant-garde artists that developed in the early 1960s. Fluxus founder George Maciunas, a friend of Ono's during the 60s, admired her work and promoted it with enthusiasm. Maciunas invited Ono to join the Fluxus group, but she declined because she wanted to remain an independent artist.
As an experimental filmmaker, Ono made made sixteen films between 1964 and 1972, and gained particular renown for a 1966 Fluxus film called simply No. 4, but often referred to as "Bottoms". The film consists of a series of close-ups of human buttocks as the subject walks on a treadmill. The screen is divided into four almost equal sections by the elements of the gluteal cleft and the horizontal gluteal crease. The soundtrack consists of interviews with those who are being filmed as well as those considering joining the project.
This is the shorter 5½ min. version of 'Bottoms' also known as Flux Film No.16.