Actually there are no such thing as beneficial mutations. Plus the first sentance said that eating red meat by homo sapiens produced a molecule that led to us having aids. I strongly disagree with that and I misread nothing. This guy is blaming red meat for something that is caused by certain life styles, and is covertly saying red meat bad, veggies good.
Sorry, that's a creationist falsehood.
The important thing to remember is that any mutation is judged to be beneficial in relation to its environment.
The mutation in early Europeans that allowed light colored skin, for example, allowed the population that carried that mutation to live at high latitudes because they could produce more vitamin D from sunlight on the skin.
Darker skin, such as originated in Africa, prevented much of the ultraviolet from reaching the lower skin layers. This was for protection from the harmful effects, but with much less intense sunlight at higher latitudes light skin was a beneficial mutation. The same mutation in sub-Saharan Africa would not have been beneficial.