Originally Posted by TennisCJC
Here's a video/slide presentation that shows Federer has very little wrist movement just prior, during and after contact.
Sometime the racket recoil will cause the stringbed to open or close but this is not controlled by the player's hand or wrist, instead it is just a function of hitting off center. Hit low on the racket face and the angle may close after contact, or hit high on the racket face and the racket face may open. Hitting high or low is in relation to the ground and not the throat or tip of the racket.
That is a terrible video. The angle highlighted is not the angle of the racquet head. Not even close. Worse than useless it's misleading.