Mozilla is trying to incorporate the VP8 codec of WebM video into the HTML5 web video specification.

Mozilla Chief Executive John Lilly, replied on being asked about this saying,

We’d love for VP8 to be specified in the HTML5 standard. Once it’s in the spec, it can really get better traction from other players.

This is a bold move by Mozilla as most other browsers are in support of H.264 currently. If this change is made, adding videos into web pages will be as easy as adding jpeg images. The current implementation of HTML5 video has no standard for video encoding and requires the web page developer to incorporate all popular web formats for the video in the page to be available across all browsers.

Before Google released VP8, there was tough competition between H.264, preferred by Apple and Microsoft, and Ogg Theora, backed by Mozilla and Opera. Now, with its better quality and open source nature, VP8 has better winning prospects in this race.

The next move Mozilla needs to make is to get some allies to support VP8 alongside itself. VP8 already sees some favor from W3C which says,

WebM/VP8 has the potential of providing a solution for the baseline video format of HTML5.

Apart from Mozilla and a part of W3C, Microsoft also supports VP8 and we too expect to see VP8 as the default HTML5 video.
(Source)