is this just alternate picking but instead of moving around different strings its just kept within a 2 string range?
It's speed picking, like BYOB or Angel of Death something
I've only heard tremelo picking on 1 string though, dunno about 2
it is alternate picking as fast as you can eg.parts of eruption

Tell me what nation on this earth, was not born of tragedy-Primordial
It basically means alternate picking very fast, nothing more complex then that.
how in the hell do you do picking that fast anyways? find the thinnest possible pick and go at it like a manman? or is there a technique?