[PS2]Britney's Dance Beat

[MarieRose1301]

This is a very old game (2002) but it has animations based on real choreo so I wanted to extract those, but I'm not even sure where are they stored... There are pss files(movies), ivb files(sound), some irx files(not sure what are they for) and iv files which i think are the archives for each song(but they are more than 700mb each)
Maybe this format was used in some other games? If anyone knows something please comment
Here's one of those iv files: https://www.dropbox.com/s/xcll6hxk5cgpsbu/Baby.iv?dl=0