The Mysterious Monsters (1975)

One of the many notorious 70's "unknown" documentaries, The Mysterious Monsters, released in 1975, covers topics such as Bigfoot and the Loch Ness Monster. Pictures, sounds, and videos of these two monsters are examined by Peter Graves, the host. Psychics, hypnotism, and the history of Bigfoot in many ancient cultures is also scrutinized.

https://m.imdb.com/title/tt0073427/