Has Butch Davis earned the benefit of the doubt? Well, I would say so.
The issues that he is addressing in the video are detailed by Dave Curtis of the Sporting News. Davis' history is actually quite strong.
As he detailed, when he was at Miami, the programming was facing significant sanctions. Under his watch, they were clean.
The name Nevin Shapiro is big in Miami, based on claims he made over the summer about the Miami football program. Those are detailed by Charles Robinson of Yahoo Sports.
But read the opening sentence of Robinson's report:
A University of Miami booster (Shapiro), incarcerated for his role in a $930 million Ponzi scheme, has told Yahoo! Sports he provided thousands of impermissible benefits to at least 72 athletes from 2002 through 2010.
Davis left Miami after the 2000 season to go to the Cleveland Browns. Formulate whatever opinions you want on Shapiro—by his own accounts, the wrongdoing came after Davis' tenure.
In terms of credibility and how much Davis knew at North Carolina, his past would suggest that he was rather innocent.
Where I don't agree with Davis is that I do feel he needed to be fired. When scandals hit colleges, the head coach needs to go. It makes sense. Even if he had nothing to do with whatever the wrongdoings were, the head coach is in almost all cases the figurehead of the football program and needs to go when things go far south.
Additionally, Davis' record at Miami was not particularly great. They were stripped of 16 wins. With those wins, the Tar Heels were 28-23. Not bad, but not good enough to keep a coach around in the middle of a scandal.
Still, Davis was right to put this video out. If nothing else, it's just nice to hear his account of the story. Obviously, you can judge for yourself, but he seems quite believable. His record certainly works in his favor.