HighMem

1. Install gxine
2. Install w32codecs (google for it)
   
3. Create symbolic links to the following files in your Mozilla plugins directory (could be ~/.mozilla/plugins): gxineplugin.a gxineplugin.la gxineplugin.so (might be under /usr/lib/gxine)
   This crashed frequently. Install mozplugger instead!
   
4. Delete the pluginreg.dat
5. Add the following to /etc/mozpluggerrc or modify anything similar to
   

   application/x-mplayer2: wmv,asf,mov: Windows Media
   video/x-ms-asf: asf,asx,wma,wax,wmv,wvx: Windows Media
   video/x-ms-wmv: wmv: Windows Media
   stream noisy ignore_errors: gxine "$file" 

6. Start Firefox, Quit Firefox -> pluginreg.dat was re-created
7. Done

Note: The lines above may already be present but pointing to mplayer. So if you have mplayer installed you need to modify only the last line (i.e. the command to be executed).