ok whenever i scroll down myfirefox its not a smooth page which comes down n even when i play my vid in small size its ok but when i play it full screen its not not fluid at all i recently formatted my pc(yest on xp ) n did installed all teh stuffs but what i wonder which one i missed
First check the screen resolution settings in display properties and then chose the best option from there. Then check for display drivers in device manager. Often reinstalling drivers resolve these problems.
Then it should be a problem with your VDO driver or hardware... Also try installing direct X 9 or later..