I just found this: a film by British artist and film-maker Tacita Dean, of Merce Cunningham, the extraordinary old man of American contemporary dance, rehearsing his company over three afternoons in a former Ford assembly plant overlooking the San Francisco Bay. I love watching contemporary dance on stage, and the opportunity to watch the less formal process of the choreographer in person creating a performance, in a film made by a very creative film-maker at Cunningham's invitation, is almost too good to be true. Cunningham died, aged 90, soon after the filming was completed.
It's being shown at the Frith Street Gallery, 17 – 18 Golden Square, Central London, between 13 May and 23 June. There are three screenings a day during the week, and two on Saturday. Details are here. No entry charge is mentioned, and the gallery is normally free.