I'm not really too sure, but it seems like you downloaded the Hulk from somewhere and it not the actual DVD disc.
For one, it could be a "screener" (someone takes a hi-tech camera and records it themselves in the theatre), or, this could be the leak earlier this year that someone within the movie entertainment industry leaked out. If this is the case, then subtitled definitely would not be included.
I don't know if DivX has built in subtitled support or not. Maybe the DVD or the person who ripped the DVD did not include subtitled.
Maybe you should just buy the movie (although I heard it sucks. lol)?