A simple shoulder rig

I have made an explanation movie about making shoulder rig. In this movie I make very simple shoulder rig. I used expanded version of that for Rider's shoulder or wrist.

Part1 of 2http://www.youtube.com/watch?v=I5hPOsefqYE
Part2 of 2http://www.youtube.com/watch?v=wkbS-rCSwCk

Speaking English is fun for me, but if you cannot get it, you can download a sample file from this page
http://nkj.lib.net/sculpland/htmls/english/modeling/08modelinfos.html
The file is "19HowToMakeShoulderRig.zip".