A little lean back at contact:It sounds like you believe she is leaning back to lift the ball. I believe the lean is a result of her trying to put more power into the swing.
But after contact and follow through:
More head lean back:
I see the hitter leaning back to get 'more power' into her swing. More 'push' from her lean back.
Using the pole on the left side of the screen for point of reference.