The Hobbit (1977)
directed by Jules Bass & Arthur Rankin Jr.
Related poll: Favorite film adaptation of The Lord of the Rings
You can watch it HERE for free.
The first ever released 'film' based on Tolkien's works (actually, it's more of a slideshow with music and narration). It is loosely based on The Hobbit novel, and was made solely to extend the adaptation rights. It was screened at a single movie theater.
The runtime is 12 minutes, and you can watch it HERE for free.