Here is another series of progressions:
Thank the Creator for the mute button.
And one more:
The easiest, quickest, and simplest technique I've ever experienced in teaching back twisting is Wade's recommendation: Set, pull the arms down and pin them over one thigh. You don't even have to drop one arm ahead of the other or pull it off to the side first.
Further tutes:
Twist direction with Glenn Vaugn
Layout and twist drill with Neil Resnick
Back with full on trampoline
Twisting progression with Doug Byrnes
Twisting progressions part II
Twisting drill with Kip Reed