If there were criteria, then it would be a book instead of music.

BTW, in the show in Italy (Palasport in Bologna), the first song is mostly a warmup.

The audio was created by a Dutch fan, who mixed together three different audience recordings:

1st Source very lightly in the middle.
2nd Source on the left.
3rd source slightly off centre on the right.

I agree with Numbersixx, I don't hear anything particularly metal about those Jimi clips beside the overdriven guitar tone.  Helter Skelter is much closer to early metal like Black Sabbath than Jimi is.  Hendrix still has the psychedelic blues sound to his playing.  No amount of tube amp breakup makes that metal.  The driving, bass heavy, distorted sound of the guitars on the Helter Skelter gives it a darker, more menacing sound that just doesn't exist in the Hendrix clips.

Maybe if you are considering the guitar tone and marshal stacks exclusively then it is a precursor to metal, but even then it is a bit of a stretch considering the Beatles did it earlier.  Led Zeppelin I was recorded only a few months later and if you are looking for a natural progression towards the metal sound then you have identified the wrong Jimmy.

This wasn't a doctoral thesis.

Yes, clearly not, but is it (it being "arguably the first full 100% metal - two Marshalls, 16 speakers") not the crux of the original post and not some throwaway point?  If the post were simply, "hey, check out this awesome video of Hendrix with a Marshall stack and array of speakers", then I'm sure most people would enjoy it without questioning your understanding of the metal genre.  To simply dismiss Thujone/Numbersixx/Stapsy's reasonable question/confusion with this post is unfortunate.