Channel Awesome was run by a guy named Mike Michaud, who was a really shit boss. Pretty much anything you expect HR to do is something he neglects. Harassment was rampant, contributors were scripted into situations that they weren't comfortable with, nobody was notified about massive changes to the site, the works. Some stayed quiet because they feared retribution from man child Mike, others were either fired or quit in protest. This all bubbled up for years until a 70 Google doc detailing every single instance of neglect and hostility that went on behind the scenes was published, at which point CA collapsed like cheap cardboard. The document is freely available online, but since you're looking for a short version, I'll just summarize thusly:

Mike Michaud is a parasite that feeds on content creators and gives nothing in return. Also, his stench attracts roaches.