Added pomf.se WebM and MP4 support

Added support for WebM and MP4 video formats for the website http://pomf.se

Request from Reddit: http://redd.it/293ee6
what will your code do for a browser that doesn't support one of these two formats?

Firefox only supports MP4 on certain OSes.

Opera doesn't support MP4 at all.

Safari doesn't support webm at all.

http://caniuse.com/#search=webm

http://caniuse.com/#search=mp4

this is why we haven't added native mp4/webm support to date, because we need to work out what happens when your browser doesn't support it.