The next video that you take I'd suggest viewing from behind along the line of the ball's trajectory. It is difficult to to see some angles from that viewpoint, such as the angle between your arm and the racket when the ball is impacted.
Example,
http://vimeo.com/21512296
ITF Camera positioning for serve. Recommends camera behind net under trajectory. Behind as above works well also.
http://en.coaching.itftennis.com/med...788/109788.pdf