Maybe file wasn't found?
Edit: sorry, I was too blinded at the first look, try this:
STRING* names[10];
void main(){
str_cpy(names[0], "song1.mp3");
var bg_handle = media_play(bg_sounds[0], NULL, 100);
}
Thing is, that you can't set string like "string = "blahblah", you have to use those 'str_' function, to deal with strings. I hope this helps

Greets