http://kb.mozillazine.org/Windows_Media_Player

https://addons.mozilla.org/firefox/220/

Next One Is One Of My Favs:

https://addons.mozilla.org/firefox/201/

For Bookmarks:

https://addons.mozilla.org/firefox/2469/

https://addons.mozilla.org/firefox/1508/

And IF you are worried about you rcontent being on bit torrent or just seeing what "apps" are out there -

https://addons.mozilla.org/firefox/2607/