If you haven’t watched the Gus Van Sant directed 1991 film, My Own Private Idaho, you should. It contains the best performances of both its leads, Keanu Reeves and River Phoenix.
James Franco became fascinated with the film and after working with Van Sant himself on “Milk”, convinced him to let him create a documentary using the behind the scenes footage of the film. He created two pieces, one being “Endless Idaho”, a 12 hour doc of BTS, and “My Own Private River”, a portrait of Phoenix. 
While Phoenix’s family initially agreed to the release of the films, they changed their mind after seeing them. We haven’t been able to find the 12 hour epic BTS doc anywhere, but we did find the River documentary, on YouTube.
James Franco discusses the footage here in this interview:
https://www.youtube.com/watch?v=z-PIM_EdCwI
