I may be confused (as is often the case) but I think he says he prefers the grip type fingering over the traditional barre chord fingering.
The progressions, strummed chords, hammer ons, and picked notes while holding those chords are the lesson, not the thumb over grip fingering.
Thats what I got out of it, but maybe you cant play what he was showing using the traditional barre with the index finger fingering.
I didnt try it so I dont know.
He also mentions he is playing A flat at the 5th fret, and in other lesson videos I have watched / learned some licks, he says he is tuned a half step down.
I may have missed it but I dont think he mentioned it in this video.
I'm pretty sure SRV tuned that way most always; just googled it and Jimi did too. So, maybe it is assumed I should have known this.