Physiology, not biology. Biology encompasses a great number of things that he knows precious little about. Did you listen to that video? Getting it mostly almost right isn't good enough. That is like mistaking your Appendix for your spleen. It isn't good.
I am a programmer. I know a lot of the details about how computers work and how I can make them work for me. I can't tell you in specifics how computer parts are made or how they've changed in the last 20 years. I can give about as reliable of an explanation for that as Nakir can about Darwin.
It isn't that he isn't knowledgeable, but rather what he is knowledgeable about. It is apparent that archaeology, anthropology, and evolutionary biology aren't the topics he's strong in.