Arm and body "rotating"? -help

Hi, im wondering, this video, was created in toon boom studio, but how do they do the sort of “rotating under arm” if you now what i mean at 1:00, and then shortly after, his entire body starts rotating, how is that done?

video: http://youtu.be/9tI8RfN2iTA?t=1m

Select your arm and using the transform tool, hover near one of the corners until your cursor turns into a curved double-arrow icon and click-drag in the direction of the rotation movement. Don’t forget to make the keyframe a motion keyframe (non-constant segment) so that the rotation movement Interpolates to the next keyframe.