Rainbow Dash is the second best pony.  I guess you told her that and it made her cry.  

The music was composed and played by the extremely talented Ibringdalulz whom you can find here:
http://www.youtube.com/user/iBringDaLULZ?blend=1&ob=0

You should subscribe to him.  

The music can be found here: http://www.youtube.com/watch?v=1f1lvD1r0C8  and here:  tinyurl.com/ibringdalulz-1000years