Projects like that are usually made between friends and aren't really expected to become THAT big. Plus, it doesn't really matter, they took the guy out of the business and took away his rightful part of it. Good thing they settled.
http://www.businessinsider.com/reggie-brown-sues-snapchat-in...
Yeah, verbal agreements aren't worth squat. At best, you get a settlement, at worst you get nothing. I'm surprised these guys didn't sign contracts amongst themselves.