I wouldn't call them hot. I might call them harry with quite the upper eyebrown bone structure though.
Africa was not always a super-hot continent, climates came and went. In either case, they probably could know to some degree the probable likelihood, but who knows if they used that informationf or the show, and, even then, it wouldn't necesasrily be 100% right, of course.
Yeah but in that sequence they are in the desert, so who knows. Anyway, you are correct that there was a large amount of conjecture and many assumptions drawn in that show, from what I recall in college, even the most seemingly minute aspects of physical anthropology are hotly debated among scholars. I think I read a book about it called "Bones of Contention" or something similarly smartass-like.
It was somewhat disillusioning to see my ancestors hopping up and down and carrying on so much (like a pack of crazy monkeys). But I guess I have had moments like that, too. And sometimes my table manners don't show much evolutionary progress, either.