Studio Binder is a YouTube channel that focuses on filmmaking and in this episode they cover the 12 principles of animation
Studio Binder (12 Principles)
I Want to be an Animator
I Want to be an Animator is a Youtube collection of free Lessons, Tutorials and Tips about 3D Animation, mostly focusing on the basics and principles.
12 Principles of Animation
12 Principles of Animation – Alan Becker has made a video series highlighting each of the 12 Principles of Animation as described by Frank Thomas and Ollie Johnston in their book “The Illusion of Life”
Animator's Resource Kit 