I'd never heard of Maker Studios (not really being in their prime demographic, I don't spend too much time on YouTube). But after this announcement, some of the stuff I've read about them makes them sound like some of those shitty podcast content networks that popped up in the mid-2000's. "Sign up with us, give us a big chunk (40% from one link I saw) of your earnings, and we promise to promote the heck out of you!"
Not a big surprise that they were a target for a buy-out. 5.5 billion views per month across their 55000+ channels, those are some pretty impressive numbers. I have no idea how Youtube pays out partners, and I have no idea how accurate this site is, but it says that 5.5 billion views would earn between 1.65 million and 13.75 million USD (which is also a HUGE variance). So, even at the low end, Maker could be pulling in nearly $8 million a year (and up to $66 million based on that site), and I presume they put the burden of paying for video production on the people that actually produce the videos, so I'm not sure what their expenses are.