There is no particularly good reason why it isn't yet implemented, except that I'm lazy. It is MPEG audio (don't remember which layer at the moment, but its obvious from a quick inspection). Maybe a general purpose player can support it already?
How about THP by jurassicPieter at 3:28 AM EDT on September 29, 2006
if we are busy about other formats then i would love to see in_cube playing thp files(only the sound). There's a thp player(with source code) to play the movies but my computer is too slow to play them realtime so the sound is choppy. And all i want is the mario kart double dash intro movie music. Oh well, maybe i should add that support myself:P
THP Player by PokeParadox at 6:45 AM EDT on September 29, 2006