Yeah for SF4 it doesn't work for online play. Though SF4 is music is good IMHO so it's no big, I always play with the game's original music and have no complaints.
Capcom along with the whole world knows MVC2's music is... shall we say limited/effy LOL so just have a little faith that they will try to come up with something.
well I would like MVC2 to allow custom music while playing online. Thanks about the demo custom music news though, I can't play it because I dont have a 2nd controller. :p