Ok - first of all he presents some analysis of statistics that show that the DNA diversity between human races is less than that what biologists use to define races or subspecies. Fine, by that definition, humanity is one race. By that definition, fine -- so what?
From this he determines that the assumption that there is significant biological variation amongst groups of humans is false, and that racial categories are socially constructed. Baloney. One example that comes to mind is the difference between East and West African runners. One strong in the sprints, the other in long distances. Or I look at the big men in the NBA - a higher percentage of blacks than in the general population, even though I am one of thousands of white men who would have given our eye tooth to be there, but I'm too short and suffer from white man's disease: white men can't jump.
He goes on to deduce that it's just recent history and racial myth. And he equates thinking to the contrary with racial supremists, such as those who might think that Europeans stand at the pinnacle of perfection, using such thinking to make it legitimate to declare the African slave as chattel. Well, since no person would admit in this day and age to such racist thinking, the contrary position must be right -- that there are no statistically significant biological differences as a group. Baloney. There are clearly such differences, just not large enough to pass the threshold for a separate subspecies.
One way I like to put the point is thus. Say I task you with forming a winning basketball team, and I say you have a choice of two players, one black and one white. I refuse to tell you anything else about these two. In such a case, your best bet would be to pick the black player. Now it might turn out that the black player was Colin Powell, and the white player was Larry Bird. In which case you made the wrong choice, for lack of sufficient information. But given what information you had, you did the right thing.
From all these false arguments, he goes on to determine that racism can be easily deconstructed -- it's just a social disease. But he has changed the topic here entirely.
Racism is unfairly prejudging someone on basis of their race. Any competent basketball team wouldn't ask who's black and pick them, sight unseen. They would find out how well they had played, and how well they could play now. And Larry Bird would beat Colin Powell for such a position everytime, as easily as Tiger Woods would beat me at golf, or I would beat Tiger at computer programming.
However he is not taking racism as this, but rather taking it as any making of statistically significant differences between the human races, which he is saying is just a social confusion which we can easily deconstruct.
I'm not sure where he is going with these confusions, but they can't possibly serve us well.