First, he's a truly amazing guitarist with a beautiful touch and control.
The technique itself is simple harmonics, but how he's doing it is different than how most use it or most learn it. If you notice, he's picking each string with thumb and middle or ring finger, and using the index (pointing) finger to do the harmonic mechanics.
I checked with the clunkier pick in one hand and index finger from the fretting hand, and there IS definitely a harmonic just a few centimeters in front of the typical pick location. He's just being very careful to place his plucking/picking hand exactly where it needs to be to achieve the harmonic with his index finger.
It's a sweet technique, and I don't know that I've ever seen it before, but it's cool as hell.