Cultural appropriation happens no matter how we feel about it. We can get institutions to change the names of their sports teams, but we can't change the way young people talk.
People have always appropriated the African American culture. Some African-American kids push back. There was a BIG argument in my class once between, in this case, Latinos and African-Americans about the use of the n-word. Partly because it is such a nasty pejorative. But also because it's an appropriation. African-American kids were saying why do you have to try to sound like us. Latino kids were saying, we aren't. We sound like us.
One Latino kid acknowledged that it was an appropriation and added he had never seen African American kids adopt the words, music or fashion of Latinos (I have), but that Latinos did it all the time. He had internalized this as Latino cultures being backward and unworthy of appropriation (

). It was an interesting conversation. Anyway kids are aware they are appropriating all the time and have different feelings about it.
I do think that white people need to be more careful, but it's nearly impossible to police the language, clothing, music, and well. . . just the behavior of teenagers.
I take the girl in the video seriously as a lesbian. I don't discredit her as a queer. As a white person, I wish she at least acknowledged that the term was taken from other cultures, that she and her friends are white and are using it the way they do. But in a way that's self-evident.
Is she an obnoxious privileged white girl? For sure. Is she also using language and living as queer in a completely real and authentic way for her? Without a doubt.