I don't think this is a new insight generally, but this study does add a new dimension to it. Apparently two-year-olds shown videos of, for example, both a man and a woman applying lipstick or both a man and a woman putting on a tie pay more attention to the atypical video (that is, man applying lipstick or woman putting on tie). The researchers theorize that this is because the typical scenarios are already very familiar to the two-year-olds, while the atypical ones are not, and kids that age tend to pay more attention to the unfamiliar.
So I wonder if this study also shows, to some degree, that if we expose our kids to all kinds of different people (nothing dangerous, obviously), they'll grow up being more accepting of differences because those differences won't feel unfamiliar to them as they start to understand the world in more complex ways. Maybe that's reading to much into the study, but maybe not. After all, it seems like at some point in childhood kids learn that some differences are bad or at least inferior. Maybe this kind of insight points to a means of heading that off at the pass.