Today's free video is about quaternion rotations, a simple harmless little checkbox, but one which when explained can save your sanity. You know how sometimes objects wobble around badly when you rotate them? well yeah, it fixes that, have a watch here.
If you like this one, consider grabbing the whole lot. Good for anyone that has never animated a thing in their life, good for professionals who want to know about all the cool buttons they're probably missing.