With some tricks, you can watch Youtube videos via the Windows Media Center, but the Windows Media Center can do much more! You can also play all of your iTunes files in the Windows Media Center.
Normally, the Windows Media Center does not support m4a and m4p music files, so you’d first have to convert your music files into another format that the Windows Media Center is able to play. Thanks to a handy plugin called MCE-Tunes you no longer have to convert your files. MCE-Tunes will add support for many audio formats to the Windows Media Center.
After installing MCE-Tunes use the playlist merging utility to merge your playlists. Simply click on merge and you’ll be able to play all of your iTunes playlists in your Windows Media Center. If you often buy new iTunes, you can use the auto-merging feature to keep your playlists up to date.
If you own the pro edition of MCE Tunes you can even watch all Apple videos and TV shows in the Windows Media Center (as long as they are authorized). Additionally, you can play all of your iTunes files via the XBOX360 Windows Media Center (PS3 is not supported!) using the Media Center Extender.
To watch your iTunes videos, simply select the video, open the Windows Media Center and click on Online Media / Program Library from the main menu, then select iTunes Videos.
You can download MCE-Tunes over at http://www.mcetunes.com/