If you watch the video Akala is very clear that cultural appropriation does not have to be treated racially or by placing hard boundaries and boxes on people. He talks about how he learns a Chinese martial art, but acknowledges its cultural source. This isn't about saying white people should not rap, and forcing it into that box is creating a strawman argument (I don't think you are doing that to the extreme many tend to do it). The actual position is completely reasonable and merely about respect and acknowledgment. That people fight against providing that comes across as extreme entitlement. If you write a paper and reference your sources, that is considered reasonable. At the larger cultural level there isn't necessarily one person to acknowledge, although sometimes there is, and there is always a cultural source to acknowledge.
The 'pattern' for cultural and race has some similarities in terms of choice and free will.
No one really chooses their race background and no one can really change it, sadly.
And also the same is about cultural background. I can't really quit my cultural background, but I am in no way attached to it because I don't identify and see myself in my own culture, I don't have a feeling that people from my own country are my own people.
This is not the same for authorship at all (cultural 'authorship' vs actual 'authorship').. Actually, the original authors (the ones that are actually people with blood, heart and brain) sometimes have their creation stolen by culture, some people should be the 'rap creators' yet we don't know them, they don't really have the respect. Just the so-called 'culture' does. The culture did appropriated from their creation in the first place.
But this cultural appropriation concept does a good job into trapping people inside their cultures because it will make me and lots of people an outsider wherever I go unless "my own culture". And there is a link between culture and race, so the rap culture is populated by majority of 'black' people, it is not the same because not all 'black' people are on the rap culture and there should be a minority of non-'blacks' (with some faith) that are not from the rap culture. And I had been already called a racist just because I don't like rap exactly because of that connection (I am not much found of Eminem either).
The issue raised in the video is that the music industry has given financial and promotional preference to some white rappers when the actual style comes from outside their culture. It isn't about not letting people of other races perform hip hop or rap, but to not overrun and supplant the original people.
This isn't as much an issue for causal listeners and fans. No one is saying that everyone shouldn't appreciate an art form. The only comment in that direction was about the use of the N word, which is more of a racism issue, but still worth discussing. I did share an article about that.
The N word should be a US thing because I have no idea of what that means...
But a friend of mine once told that if you get to US you shouldn't go out saying 'Yo!' if you are not black because they get offended (some people like saying "yo!" just to look cool or just to say something different than the usual hi & hello), but I really don't like that, but if I ever happened to be on the position I would avoid the 'Yo!' just for my own self-preservation.
But getting to the point, the main problem is exactly what I had said earlier: 'Black' people have in general less chances at the music and perhaps at arts in general (at the same way of non-north american people) because basically the 'whites' simply will completely taken over the departments. I don't think they are actually wrong into trying to block 'whites' from coming to rap, because at least the so-called "black people" will at least have one department where they have good chances. For example, although we got Pharrel Willians, outside these closed culture circles we don't get a band of people who look like Pharrel Willians in terms of skill colour, like a band full of 'black' people. Yet the 'music world' is very populated by bands where all members are 'white'. So having these 'niches' where whites are blocked to join are their way for getting a chance into having fame in the music world. The real problem is that the 'white people' always take over.