I own all of the books mentioned above, as well as the flipbooks. They're really great, but you have to have a certain appreciation of animation beforehand to enjoy the details. It's really just the flipbooks - no accompanying text or anything. It gives you great insight into how talented animators animated certain movements, but you have to know what to look out for.
Not Disney, but the Animator's Survival Kit is also heavily recommended. Also recommended: Timing for Animation. I also have been meaning to check out "Elemental Magic" (2 volumes, about animating substances such as water, fire, etc.), and "Setting the Scene".
/signed a computer scientist who wishes he can retire and attend CalArts on his startup millions ;)
There is book that the linked-to animation is based on: The Illusion of Life: Disney Animation by Frank Thomas
Two other Disney animation resources that I've picked up over the years include:
* The 2 volumes of Drawn to Life: 20 Golden Years of Disney Master Classes by Walt Stanchfield
* Walt Disney Animation Studios: The Archive Series in 4 volumes: Story (about storyboards not writing), Animation, Design, and Layout & Background
I haven't seen the flip books they released recently for each of Disney's "Nine Old Men" but it sounds interesting.