My lossy PNG compressor (<a href="http://pngquant.org" rel="nofollow">http://pngquant.org</a>):<p><pre><code> pngquant --ext .png -f --quality=80-100 *.png
</code></pre>
halves size of the page with little quality loss.<p>Still, a high-res video with alpha transparency made with "codec" that doesn't compress any redundancy between frames is going to be big.