The problem is most likely because you don’t have the Windows Media Player plugin installed for Firefox, so all we need to do is install it.
Note that you’ll usually have the same problem anytime you try and view video files in FIrefox using Windows Media format, such as .wmv files.
Installation
Just download and run the plugin installer linked below. You’ll probably want to close Firefox during the installation.
Verifying Plugin Installation
After running through the very quick installation wizard, you might be curious if the installation actually worked. While the easiest method is to just open a Windows Media video, you can also type the following into the address bar to see the list of loaded plugins:
And you should see the Windows Media Player plugin in the list. You can also see which file types Firefox will use the plugin on.
And now I can view this Windows Media format video file in Firefox…
Technical Notes
In case you have any issues with this installer, you might want to take a look at this list to help with your troubleshooting:
The WMP plugin uses the IE Proxy settings, not the ones in Firefox. This is because the plugin itself is only a thin wrapper around Windows Media Player, which always uses IE internally to fetch data. The plugin files are installed to the “C:\Program Files\Mozilla Firefox\plugins” directory by default, and the file name is np-mswmp. dll. If the uninstaller fails to remove this file for whatever reason you can manually delete it. You could also theoretically copy the same . dll file into the plugins directory on any Firefox installation and it should work without running the installer.
Download Windows Media Player Firefox Plugin from port25.technet.com [source]
