Though I do get annoyed when people who aren't fully something will simply say that they are. If you are a mix, say so, its pretty simple. I guess people like being associated with something.
I don't usually post in these kinds of threads because I think they can become hurtful. I can't see your opinions on YouTube on my phone but I'm one of these people who is mixed but just says I'm black.
People ask my ethnic background all the time and I just say I'm black because I don't have time to explain my mix. My mother is of mixed race but its not easy to explain, as people then ask what she's mixed with. There are no 'black' people on my mothers side of the family for centuries but she is a 'Cape Coloured South African' so she is mixed, but with what?! Its hard to specify. They are mixed race people who are not 'half' of anything. Some of them look 'black' and others, like my mum, don't. They are still all of the same 'race'. Hard to explain; the labelling does come to down to the apartheid and segregation.
I just find it easier to say I'm black. If I have time to explain my family tree, then I will. But I rarely have time. It doesn't mean I do not identify with both sides (or the multitudes of sides) that make me.
Also, I often get people rolling their eyes if I try to explain my mix. It's as if they think I'm clutching at straws to try and be 'less black', which I would never do. (I have come across many people, especially in my younger years, who feel the less 'black' you are, the more attractive you are and I never want people to think that I feel this way) So to avoid confrontation, debate or confusion, I say I'm black.