Windows Media Player HTML5 Extension for Chrome
The Windows Media Player HTML5 Extension for Chrome is an extension that
enables Chrome users to play H.264-encoded videos (aka MP4) on HTML5
pages by using the built-in capabilities found in Windows 7.
Important Notes:

If you are running Windows 8, the extension will NOT work. We
recommend that you download Internet Explorer instead. IE is a
modern, standards compliant browser that remains compatible with
older media technologies.

If you are running Windows 7, and your Chrome browser is version 33
or newer, the extension will NOT work. This is due to an
architectural change in Chrome. The reason was articulated by the
Chrome team in this article. As an alternative, we recommend that
you download Internet Explorer instead.

If you are running Windows 7, and your Chrome browser is version 32
or older, you will still be able to install the plugin by following these
instructions:
1. Download the extension from here by using the right click and select
"Save Link As..." (DO NOT just open the link by clicking on it) and save it on
your local machine.
2. In Chrome, select the menu Tools/Extensions.
3. Check the "Developer mode" box.
4. Drag & Drop the extension file (copied in step 1) on the extensions page
in Chrome. Chrome will ask you to install the extension.
Windows Media Player HTML5 Extension for Chrome Release Notes
License
A copy of the license agreement is available here (A copy of the file is also
installed with the Add-on).
Release Notes for Developers
This Extension is based on a Chrome Extension that parses HTML5 pages and
replaces Video tags with a call to the Windows Media Player plug-in so that
the content can be played in the browser. The Extension replaces video tags
only if the video formats specified in the tag are among those supported by
Windows Media Player. Tags that contain other video formats are not
touched.
The Extension also checks if the browser version already supports MP4
(H.264) video codec, if so the extension is not used.
The current version of the Extension still uses the Windows Media Player
Plug-in APIs to control video playback, so there are some differences
between the methods/properties defined in the emerging HTML5 standard
and those available in the Windows Media Player plug-in. We are working to
fix this limitation in the next release.