I had a convoluted method using gifsicle to extract the frames and then encode as a stream of frames, but then sometime in the past year or so ffmpeg improved native gif support. This is what I use (the options are both for compatibility):

    ffmpeg -i foo.gif -pix_fmt yuv420p -vf crop=floor (in_w/2)*2:floor(in_h/2)*2 foo.mp4

Works for WebM just by changing the extension, too.

Check out http://www.gfycat.com/about

imagemagick + ffmpeg

https://stackoverflow.com/questions/3212821/animated-gif-to-...

I made a website that does this, and a lot more. It's also open source, and has been around for a while.

https://mediacru.sh