single line legs (AS Tutor Freebie)

[exile]

http://www.animestudiotutor.com/freebie offers us an AS File with 3 examples of single line legs. I had seen a similar construction in the "new features of Version 10" webinar with the yellow blob man, but these new single line legs work with bones. After some experimenting I could recreate the complex "kid" legs. The ones in the Tutor file work with both legs in one layer, which I couldn't make work for me. The extra layer I ended up using is not a huge problem, but reducing layers is a cool thing. Does anyone have a clue how these two legs on one layer move independently with bones ?

There was no possibility to ask questions or comment on this item at the AS Tutor website (just to anticipate someone referring me back to where I got the file). Single line legs are a great idea for some characters.

As always, help is appreciated.