Legal? Looks kinda leapish but she is dragging and not replanting. I have my own thoughts on it but wanted to see what the board thinks.
In examining both pitcher's drive leg, IMHO:
Frame 1 shows a loaded drive leg
Frame 2 shows a drive leg that has unloaded (extended).
Frame 3 shows a re-loaded drive leg
Frame 4 shows a drive leg that has unloaded (extended).
Without closer detail it is hard to say, but I would be surprised if she is not getting airborne. Note the turn of the plant foot as she breaks contact with the pitchers plate.
Try this at home. Simulate coming up and out from the pitchers plate while turning the rear (plant) foot 45-90 degrees.
hard to tell if there's any air under the drive foot, but to get to the edge of the circle with a proper drag, those would have to be some pretty powerful legs.
very high stride knee just to get to the edge?