It’s not really pivot the back foot.
No, they disengage from the rubber earlier around 5:00 in the upswing of the arm as they coil and rotate open.
Would also think this style would be nearly impossible to use with Ball in Glove?
These mechanics look very similar to hitting. Using the the back leg to 'snap' the hips in place to lead the upper body.
Would these mechanics be easier to teach. Lots of carry over from hitting, throwing overhand, ect...
Good posts adding both video and still frames in your discussion!