Bug the news songs of minecraft

Hello !
When I open Minecraft, i can play but the nexws songs of the game is saturated :
http://www.youtube.com/watch?v=Dh-Kj5IeanU&feature=plcp
I have filming the bug !
What the problem ?
Because I have a Mac PPC or java 5 or a problem with the files ?
The news songs is perfect in snapshot 12w38A but in snapshot 12w38B, they begin to saturated !

I am french sorry for the spelling and grammar !
Thanks for help !