Its kind of the same technique, Your computer is far more advance than the xbox becuase of the applications it has, Also windows media player, Music match and most programs that are to play music files normally check the internet and match up the track list and copy that list to give you the names it needs for the tracks. Oh to the wonders of the internet! I use the same technique at the moment using my pc to copy and transfere my music to the Xbox
You may be thinking that your Xbox is connected to live and why doesn't music mixer look up on live for the track names, thats because of a few reasons, Music mixer is not smart enough to look on the net for the tracks also there is a very big charge normally come with this software.....hense they didn't put it in to keep the price down!
Forgiveness is between them and God, I'm just here to arrange the meeting!!