From what I understand those 50 millions will only be paid with assets from grooveshark. If groovershark the company doesn't have assets to cover the 50 million they will not get paid and also can't get paid from the individuals.
There have been large settlements in the past that turned out to be false. They want a high number for shock value, but nobody's actually paying it. (There was something to that effect in the sony docs iirc.) See: Hotfile, Isohunt, etc.
Keep in mind that the founders were also sued personally (it's a common tactic by the labels). The leverage of the settlement was to keep the entirety of the 50M due within the company and not be personally liable as individuals for the amount (for life).