Below you'll find a YouTube video of "Les Maîtres Fous" ("The Mad Masters"), a 1955 ethnographic film by Jean Rouch (1917-2004).
I cannot recommend this fascinating documentary highly enough. The film depicts a violent ceremony of a Ghanaian possession cult "Hauka" - the images are of a beauty that is truly convulsive.
At the time, reactions to the film were as strong as the images the film contains: it was banned in Britain and the Gold Coast, but received the Grand Prix at the Venice Biennale. Today, it is regarded as a classic of ethnographic filmmaking and considered to be one of Rouche's best works.