Video of tape yourself might also be art, it all depends.

That is so true. I video-taped myself making some abstract paintings a while ago, just for documentation's sake. The video ended up becoming a type of performance art in itself, unplanned.

Butoh dance

Wow, I have never even heard of it, but viewing it, I am mesmerized. As someone unfamiliar with the history and cultural situatedness thereof, I lean towards it being art. The video I watched just now of it reminds me of the lead singer frontman of the band Tool, Maynard James Keenan. In his older live performances, he danced in a very similar style. I wonder if he might have been inspired by Butoh dance.

But do we as spectators need to know the history or the creation process behind a certain style or an art piece to understand it?

This is a very thoughtful question. Like you said, leaning toward a "maybe no", and with the addition of making one feel uncomfortable, etc., it all depends right. In the end, art cannot really be bound by rules. But I am reminded of a quote by a philosopher, William Marx in The Hatred of Literature, writing about literature that does not shock one:

"To refuse literature the right to shock, provoke, and make people uncomfortable is to impose upon it the constantly redefined duty of offering readers only what they expect—what they can accept, understand, and absorb. It is to refuse the power of reading to confront us with alterity. It is to demand that literature propose only sameness, that is to say something with which readers can wholly, blindly identify, without calling on their critical and hermeneutic faculties. It is to turn every reader into an eternal minor."

I think that quote can be relevant to all art as well. And I think Butoh dance also fits in this. It immediately makes one uncomfortable if you are not familiar with it. I am not sure if this is a legit and authentic version of it, but it is one of the first when I google it:

Again, irrespective of cultural and historical significance, this dance reminds me of performance art, I struggle to fit it into any predefined notions of art, it makes me feel uncomfortable, it challenges me, it makes me think differently, etc.

Sorry for the already too long comment!

I am so glad that the review got chosen and that you find it well!