How can I get H.264 support?

Canonical Limited is shown as a licensee of H.264. I am interested in being able to play H.264 video online when using the Chrome web-browser in Ubuntu (and in the future on Firefox when Firefox supports H.264).

Is H.264 support enabled on self-installs of Ubuntu? If not, is there some way I can buy H.264 support for my Ubuntu install? Assume a scenario where I self-installed Ubuntu on a computer that came pre-installed with Windows OS. I'd like to know any and all options available to me for getting H.264 to work on Ubuntu.

The ubuntu-restricted-extras has all the multimedia decoding packages in and working for me on the decoding end. And chromium automatically used the ffmpeg plug-in.

If there are packages in restricted-extras you are sure you don't want you could try just
chromium-codecs-ffmpeg-extra from the Software Center:

Or in Terminal:

sudo apt-get update
sudo apt-get install chromium-codecs-ffmpeg-extra

Just to be sure it makes it in to chromium and you don't just get the codec.

You can get H.264 encoder by installing the x264 package with the Software Center:

Or in a terminal:

sudo apt-get update
sudo apt-get install x264

Right now, I'm using Firefox Nightly (27.0a1 (2013-10-24)) on Ubuntu 13.10. I made the change on the flag media.gstreamer.enabled to true. You also need to install the package gstreamer0.10-ffmpeg.

You can check if you have h.264 enabled in this page: http://www.youtube.com/html5