That's a version of an old trick that I first heard used by Eddie Van Halen.

Choose some repeated pattern with hammer ons and pull offs (e.g 5 3 0) played at fast speed, say on the 5th or 4th string, while using some form of muting on that string with your fretting hand. By moving the point of contact where the mute occurs, different harmonics are generated at high speed.

Easy way to do this ... just very lightly touch your finger tip on the string, nearish the bridge, and keeping that light pressure, move your finger tip at a slow speed towards the neck pickup. Using the edge of the palm is not quite as effective.

Experiment with the pressure of the touch. You'll hear when you get it right.

(Watched it again, and he's primarily just doing muting with fast hammer-on / pull-offs. There's also effects being used.)

cheers, Jerry
Last edited by jerrykramskoy at Dec 21, 2014,
Going by Jerry's description (can't watch the video right now) I've heard that called autoflanging so that's a place to look for more information if you need/want it.
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