Haha! I'd love to hear him testing mic's too! He certainly is 'possessed by the music'. I'd like to hear the bassists other work as well. We all get something different out of sonic experiences. Especially this kind of avant-garde or free-jazz. This sort of thing can really test people and challenge their definitions of art, as it seems to have done for you. It can drive them genuinely insane as well. I personally love it for that, its very punk!
His vocalisations are just that. Vocalisations. This doesn't limit him to specific words, harmony or rhythm. It could be considered quite dissonant. But interestingly, I saw a Rick Beato video recently where he discussed the idea of 'immunity to dissonance'. If you hear a dissonance or musical oddity enough you acclimatise to it and it is no longer dissonant or odd to you, just another fascinating harmony. 7/8 is 'odd' time, but we all got used to it. It's not strange anymore. Immunity to dissonance, while utterly alien at first, is central to this performance I feel.
I found it was interesting to listen to with my 'soundscape head' on. The beginning brought the image of someone working with wood outdoors to my minds eye. I'll readily concede that it's not musical in the classical sense of the word. It's not Trane, Ornette Coleman or Sun Ra, but it does have a certain something. I once went to an enjoyable free-jazz/avant-garde gig which closely resembled this but used prepared piano, drums, bari-sax and electronics in addition to voice and bass. I found it made a refreshing change from the usual diatonic harmony and evenly divided rhythmic content.
When I was younger, I remember feeling the way that you feel about this, but for all Jazz. The music was unpredictable (which I took to be bad at the time) and harmonically beyond my understanding. So, like a typical monkey I interpreted that which was unknown to be bad and avoided it. As I have matured, this has obviously and quite necessarily changed.
For me, this performance clearly demonstrated the difference between improvisation in a conventional jazz idiom (where we expect the usual cliches of approach notes, time on the ride cymbal, walking bass, extended harmony etc.) and improvisation in a free setting such as this, where any sound can be interpreted musically.
John Cage had alot to say about this. He held that all sounds/silences are musical, it is the listener and their ability to hear the sounds as such which varies.
Don't actively listen to it I say, just be part of the thing. This is what I would call "inhabiting a sound-space" or passive attention. Very meditative if you're into that stuff. Similar to when you put on a record while doing some chores. The tune simply accompanies you as you go about, you're neither ignoring nor focusing on it.
Performances like this are highly introspective, interpretive and, as with all music like this, requires completely different priorities from the listener. If everybody walks away from the performance with the same thing, then this music has definitely failed.
Think about abstract expressionist art. It doesn't ask you to recognise use of forms from reality in the work (in this case the parallel would be use of conventional musical laws in the piece). The point is not to say: 'Look how well they depicted this scene or that tree.' or 'Look how well the bass outlines harmony x or rhythm y'. Nothing so literal. Rather, the purpose is personal, unique from hearing to hearing and often difficult or impossible to convey with words.
P.S. The little "Ooo." from Minton at the end made me laugh.