I have been fighting with the Firefox browser for ages now, but decided to try one last time before I gave up.
I googled one hour and found out that I could use GreaseMonkey pluss some additional user scripts to force Firefox to play Media the way IE does it. Well, that didn't work, so I googled some more.
Every time I googled, the page port25.technet.com/... came up in the results, but I already tried that at least 10 times, so I knew that didn't work anymore.
OK, to make a long story short, I downloaded the Windows Media Player Firefox Plugin from port25.technet.com/... I then realized the installer can be opened with Winrar (maybe also 7zip), so I exctracted the files to a new folder.
In the new folder, there were 5 files:
1. I right clicked each and every file and chose "Take Ownership".
2. Then I ran the installer.
3. And to finish it up, I right clicked the INF file and chose "Install"
Guess what ?
When I launched Firefox and visited my favorite Music/TV site everything worked like a charm.