It's also very easy to take things out of context. For example, I can see someone being a defender of pure science and saying, "no topic should be beyond the purview of science. There are no sacred cows. There are undeniable differences in any number of physical features between various ethnic and racial groups. Think of how the people of Tibet and Nepal have evolved greater lung capacity to handle high altitudes. The brain is an organ like any other, why shouldn't there be differences in brain structure between certain racial or ethnic groups? Maybe some groups have slight advantages in certain kinds of intelligences and cognitive abilities."
Honestly, that doesn't sound like an absurd hypothesis at all. Certain groups have any number of physical advantages or disadvantages, why not mental advantages? This wouldn't be a universal, "this race/ethnic group is smarter than another." It would be "this ethnic group has an advantage in this particular cognitive task, this in another." Would that really be so absurd? Certain groups have advantages in long-distance running, why not in say, 3D mental object rotation, or facial recognition, or social relations management? Maybe some ethnic group that has always lived in large extended families and clans would on average be better at keeping track of complex social webs.
I would find it absurd to propose that one ethnic or racial group was universally "more intelligent" than others, but that's because there isn't just one type of intelligence. But I could easily see certain groups having advantages in certain areas. We know that physical advantages can exist, it would be unexpected if the same didn't happen to certain specific cognitive tasks.
I haven't watched the video, but I could easily see how someone could take an argument like the above and slander someone by removing all nuance and saying, "this person thinks black people are less intelligent than white people!!!"