Matt Heafy & John Petrucci - Guitar Theater, Episode 3 - YouTube
Matt Heafy is apparently an idiot with horrible technique.
He says "I don't know what it is. I don't know what I am playing"
This is pretty much Petrucci giving Heafy lessons and trying to make him feel good.
His playing seemed ok on that clip. Not brilliant by any means, but certainly not terrible