The first part gives tips on "treadmill walks" also called "cycling in space" in which the character remains in one place while the background pans behind.
BG moves at the same speed as animation
Legs should not shorten.
Legs should be on different level (to connote space/perspective)
There's then a diversion (pedagogically the diversion can be the strongest teaching tool) into a horse's tail.
Horse's tail should have straight lines to give the feeling of bone. Also gives more flow.