This is an exact copy of a REAL commercial
You can find it on LOST AND FOUND VIDEO NIGHT VOL. 7 from 5minutestolive.com. I rented this from my local cult video store and almost died when it came on (many other classic random clips as well). The real commercial is definitely not a stunt double and looks even more painful (you see the guitar clearly snap in two). I have no idea where the real commercial comes from and how PT Anderson saw it and why he decided to copy it just for the DVD release.... but I'm curious to find out. Anyone know?
-Jared