Google analytics doesn't provide an XML API to submit hits, otherwise I will developp PHP URL instead of putting MP3 URL in the XSPF.
So the consequence is that each MP3 play thru the player is not recorded in stats.
This can be disappointing if the MP3 author is the creator of the website (this is my case).
A new parameter would be necessary to get the Google ID.
I'm not a Flash developper so I don't know what is possible to do.