Of course, you have singularly failed to provide a single example of 'cultural appropriation' that you do think is a problem.
You've managed to miss the point with your twerking obsession.
It isn't just the one thing.
The culture we're talking about is one that springs from a shared experience going back to the days when people like the guy in the OP speech would have been the property of someone else. It isn't just the one thing. Music. Food. A dialect. Social norms. Clothing. Hair styles. Literature. All kinds of things existed in a culture that was (at least after the end of slavery) considered by some to be separate but equal. It was certainly separate.
What Mr. Williams was talking about was more than just Miley Cyrus twerking. It was about the white society that had owned black people for a few centuries and then oppressed them for another 100 years swooping in and "borrowing" parts of that culture when it was convenient or fashionable or profitable for them, and then selling it as if it were their idea in the first place or at the very least claiming to have "discovered" something that had existed all along in the black community.
An example I mentioned (and again, it isn't just the one thing) was Pat Boone. Little Richard - a flamboyant black man - made the song "Tutti Frutti." He wrote it, performed it, and released it. But flamboyant black men making records was a bit too threatening for 1950s white audiences, so Pat Boone (who had also covered Fats Domino's Ain't That a Shame) was brought in to sell the record to them. Suddenly the nascent rock and roll music - which had sprung almost entirely from the black community - was a white thing. Bill Haley and then Elvis were the face of rock and roll.
A decade later a bunch of white people from Britain stumbled upon the blues, and to their credit a lot of them tried to say "this is just our version of it but you've really got to listen to Muddy Waters and Robert Johnson" but it was to no avail.
And again, it isn't just the one thing. Williams' broader point was to say in effect "you love us when we dance and sing and act and play sports really well but you don't actually care about us. We're still minstrels to you in many ways, and when we stand up and demand you treat us as equals suddenly we're all threatening and scary and you need to 'do something' about 'black lives matter."
He's saying we're not quite done with the whole civil rights thing. That there's still work to do. And here we are on this thread arguing about twerking.