Going into the power pocket you are pulling your elbow down and into your body/hip (shoulder going ER and upward) collapsing the power pocket, instead of going elbow up and out (shoulder going IR and swing forward) swinging disc into bigger/deeper power pocket with later and greater elbow extension/radial arc. Note how when you come inward into the power pocket your disc edge closest to your body goes wing up, instead of wing down.
Do you think my bad arm action might be caused by my bad shift or lack of it? Do you notice, that I'm never really bracing on my front foot? The outside edge of my foot is airborn. Maybe fixing that would fix the arm action too.
Here I'm really trying to get the brace down, but the foot still in some insane way is able to not be grounded/braced. What is causing my inability to simply just brace?