Cave Story + MLP ? Two awesome things in one !
Sorry that this took a long time, but i've got Sony Vegas 10 now, so I can use high quality MP4s without having to convert them first.
Mp3 download : http://www.mediafire.com/file/v3yn1rq3rh7r3im/Twilight%20Story.mp3
The music used is the main theme of Cave Story. It's an awesome game, and it's free on PC, so I highly recommend that you try it out !

My other Pony YTPMVs : http://www.youtube.com/view_play_list?p=9731E2E91C0622CC