Ok, I think I see what he’s doing. He tunes down, then back up, then back down to get the descending effect at the beginning of the chorus. To do that without tuning you’d have to mute the string and bend it before plucking. Not only does his hand look too busy to hold that string long enough to bend it, but I am guessing with those pickups so close to the strings, you’d be able to hear that muted string scrape the fret. I haven’t tried it myself, nor am I anywhere good enough to play in this guy’s world, but based on the video, I think that’s what’s going on.
Fucking ASTOUNDING.
