Originally Posted by Tight Lines
Although hard to see, it looks like you are not doing enough pronation (forearm roll, ISR) because the racket hitting surface is pointing down as you hit the ball. It should point to the right side fence.
Just to clarify, I think you mean "immediately after" you hit the ball, not "as you hit the ball." The face has to be basically square at contact for the ball to go into the court. It should be pointed to the right after contact though.
This Safin video shows it pretty well: http://www.youtube.com/watch?v=lhrfqjokS_Q
(Contact at :54, racquet face pointing right at :55).