The following is another little example of the Path class we talked about here.
Just draw a path in the square and the yoke will follow that along back and forth.

[Download the source FLA]

Please note that when you are drawing the path there are many little red dots coming up on the screen. That is the key nodes. When you release the mouse button the amount of them reduces a lot. It happens to my algorithm of approximation which is not invented by anyone yet, I think. :)