Nice Heart of Wild Cherry Natural Elements performance.

noodling around ..at its best...

It also sounds to me from the way one note is sustaining and nearly feeding back, that this what the guitar sounds like amplified, not acoustic. Either that, or the mic doing the recording was set too hot.

The note's an Eb (which means the guitarist is hitting the low E-string with the guitar tuned down a half step, as you noted).  I hear it almost immediately, ringing suspiciously long at 0:03 - 07, and again at 0:11-15 and at 0:27 - 32. I also hear overtones of Eb an octave up in the sustain, and the note seems to almost grow in volume as it rings, which is why I suspect it's amplified (and probably too close to the speaker). To my ear, it sounds like the guitar's just on the verge of beginning to go into feedback -- if that were my Artist Studio and I were playing live, I'd be fiddling with the balance between the mic and the undersaddle pickup to see if I could get rid of that, and/or turning down the volume slightly.