That being said, I've always found that black ethnocentrism has a similar effect to white ethnocentrism: it causes further division and worsens the problem it claims to try to solve.
The statement "Black Lives Matter" offends me, because it makes the assumption that because I'm not black, I don't think black lives matter, and therefore have to be told that they do. Most of my friends growing up were black. My best friend was closer to me than my brothers, was best man at my wedding, and I at his. It also over-simplifies a complex problem, that has at its root the fact that the hostile relationship between blacks and police is not one-directional. It was started by white police with decades of oppression, but the current situation is a cycle perpetuated by the thought that police are the enemy. If you have been told your whole life that police are the enemy, then you are going to behave differently when they approach you than someone else. If the police are in a community where everyone has been taught this, they will behave in a way that ends up supporting this belief, and the seeds of conflict are sown.
Ethnocentrism has never, ever helped unify people. My personal experience growing up and socializing in a mostly black social environment left me with the impression that there is a minority of black Americans who, similar to a minority of white Americans, are ethnocentric and racist towards those who don't share their race. The difference is that the black variety of ethnocentric activists are openly tolerated and encouraged by white people who have never in their life spent ten minutes under the roof of a black person's home, let alone attended black churches or been involved in family events such as Thanksgiving dinners, weddings, funerals, etc.
Racism is a part of the human condition, as is its direct precursor, ethnocentrism. Pretending that it's different depending on the person's complexion tells me that these white folks view black Americans as different than themselves, almost less human. I hold all humans, no matter how difficult their background, to a higher standard.