[rudog]

We've been doing that at my company on our mobile applications for a few years now. There is no reason to be shoving 5-10mb GIFs down a users throat on a mobile device. Not only does are MP4s smaller (file size), frames per second will be constant on all browsers, unlike GIF (although most browsers are supporting up to 50fps these days). Although outdated, you can read more about that here. http://nullsleep.tumblr.com/post/16524517190/animated-gif-mi...

I wrote a simple js lib for detecting the duration of a GIF for each browser. It was a fun weekend project. https://github.com/rfrench/gify

If webp gains more adoption, it's another alternative now that it supports animation.