If the movie size is absolute - using specified pixel dimensions - one has more control over the frame rate. If a movie is larger than the region that will display in a browser window at 640 by 480 resolution (see below for actual pixel dimensions of available area), some users will not be able to see the whole movie at once, and will have to scroll to see the other parts. If the movie is scaled to the browser window, the movie will run considerably slower than might might be expected on large displays.