Toly, thanks for the great analysis. I do think I still have slight "waiters tray" in frame 1, but its not as bad as it was in the first set of videos, so that is promising. I am continuing to work on that. My palm is not facing 100% upwards, but about 45%.
And yes, I believe that diagram is of a kick serve, which I am not working on right now, so its not exactly what I need right now, but I do appreciate it. You can tell how the ball was tossed behind his head.
But back to your point of pronation...it looks like there is some pronation going from frame 3 to frame 4. So what exactly is my issue here, in terms I can understand and try to fix? Am am pronating too early and not enough? What steps do I take to fix? Again, be realistic about what's "fixable".