It's "The Pixar Story"[1]. A great documentary, highly recommended.
But Pixar wasn't all roses either - during the tight production of Toy Story 2 (because they changed almost all of the story and had to rush it for christmas), a couple (who were both animators) forgot that their 1-year old was in the car (and not in the day care!), and the girl was there for almost 10 hours... She lived, but still a pretty horrible story.
The source for this unpleasant anecdote is [2]. It's a long talk by Ed Catmull, but I can't recommend it enough. It's really, really awesome.
Success hides problems (Ed Catmull)
Want to know why Pixar was awesome for soooo long? It wasn't luck, and it wasn't because they had great animators. It wasn't even (entirely) because they told terrific stories. It was because they constantly learned from their "successes"... Watch (or listen) to Catmull's talk. I guarantee that you won't regret the 55 minutes you spend on it...
Whats the name of the documentary btw ?