I was trying to analyze the picking motion of Kevin Heiderich, but since I only recently got a subscriber again and am not yet that much into the motion analysis stuff, I need a little bit of help.
So far I see a lot of wrist movement and I think it is mainly upstroke escape. I think the forearm is supinated (I hope that is the right term) a lot because you can see a lot of the underside of the forearm. You can also see a lot of forearm rotation if he plays chords or string skipped single notes, which he also does by moving his whole arm position up and down (or back and forth) a little bit. His pick grip seems to be some sort of in between trigger style and angle pad?
The thing I am very confused with is, he plays a lot of very crazy stuff and at least for other covers he did (songs by Necrophagist) he needs a lot of downstroke escape strokes as well. But I don’t know how he does this. You can see that he has some kind of turn in his hand then but I am not able to interpret what I see. It could also be that he swipes at least some of the notes he plays.
Since this guy has one of the craziest picking hands I have ever seen, maybe somebody is willing/interested in looking at his hand.