Below is a link to an excellent documentary on the History of Disney Animation, titled It All Started With a Mouse. It was broadcast in 1989 - so it does not include anything from the digital era - but much of what the Disney Studio achieved is timeless, and still holds up well today. Think of classics like The Jungle Book - still great entertainment 40 years later. In short, this is an excellent documentary on the history hand-drawn animation at the studio up until the late 1980s. The video is hosted at YouTube (for some reason I can't embed the video here) but if you follow this link you'll find it. It runs an hour and a half, and is an excellent introduction to the medium of animation.