It’s just about thinking that way of greeting people with a silent awkward smile/smirk is weird, and associating it (as the video header does) with white people. You can see in the many comments on that Facebook link you posted what the range of thoughts about it is. It reminds me of a comment some people have made about some suburban people putting on an air of fake nice greeting when they meet a stranger but it not seeming authentic. It’s just a case of different mannerisms and people reading into it and maybe being accurate or unfair in different cases.