http://www.imdb.com/title/tt0438832/

I had the pleasure of seeing this at a festival. Would love to catch it again.

Although it's not really horror or anything, it is about the sacrificial ceremony which takes place every hundred year in Bali, where the inhabitants have to throw one specimen of every living thing on the island, into the dormant volcano, in order to save the cosmos from destruction. The spectacle is quite baffling, on account of the intensity of the worshipers dedication. The narration is by none other than Orson Welles.