The Roaring Silence - Buddhism Documentary 1978
Filmed by Petere Montagnon for the the BBC travelled to Nepal to look at the Tibetan Buddhists and their practice there, and in doing so provided an immensely valuable record for the years to come.
The film begins in Kathmandu and visits Tangboche, in Nepal, in 1973. Published in 1978.
Film details here: open.ac.uk/library/digital-archive/program/video:00525_3433