html5 video and a good codec are a way better use of bandwidth.
This technique is good for animations with few moving parts. For example the Alfa animation http://www.divergentmedia.com/phosphor/gallery#alfa needs to download 14 additional images for a total of 3.5 megabytes for a few seconds' worth of animation.
if you are animating the movie, just export from your app as prores. that's how some of our gallery clips are done (the logo spin for instance in blender 3d model rendered straight to quicktime)