Flash movie has issues with parallax technique

I have created a site using the parallax technique. I have used a transparent flash movie with animation on the front parallax layer and when the mouse curson is on top of the movie the screen seems to tremble in contrast to the rest of the site in which the move see开发者_开发问答ms much more smoother. I am not sure if is has anything to do with the size of the movie. It has a width of 1450px and a height of 825px.

Thanks in advance