You can restore the standard WMP plugin files that are normally included on most Windows XP and earlier operating systems.To check for these files, type about:plugins into the location bar.You may visit a site that includes embedded media requiring the WMP plugin and receive a message such as Unknown plugin (application/x-mplayer2)  or you may be incorrectly directed to reinstall the WMP program, which is not a solution, since reinstalling or updating Windows Media Player does not add the missing plugins .If your system is missing the WMP plugin, use one of these solutions: Firefox and Sea Monkey users on Windows XP and above can install the Windows Media Player Firefox Plugin provided by Microsoft.Windows 7 users can install the HTML5 Extension for Windows Media Player Firefox Plug-in, which adds an extension that allows playback of H.264-encoded videos and additionally installs the WMP plugin by creating a C:\Users\App Data\Roaming\Mozilla\plugins folder and placing the file "np-mswmp.dll" in that location.Warning: This extension has been reported to cause excessive memory usage in Firefox 5 or above.If your system includes the standard WMP plugin, make sure that it is the updated version of this file.
VLC runs on all versions of Windows, from Windows XP SP3 to the last version of Windows 10.
Instructions for installing the new WMP plugin in Firefox or another browser are given below.
The WMP plugin test pages Thailand Videos at and Windows Media test at contain embedded media that require the Windows Media Player plugin.
If you installed the HTML5 extension and are having problems, open the Firefox Add-ons Manager Extensions list and remove it (the WMP plugin itself will remain installed).
     The standard WMP plugin will work on most Windows versions and Mozilla-based browsers but it may be missing functionality that the new WMP plugin offers.