The question you raise at 2:00 - 2:20 "why do we prefer average faces" has an obvious answer: we do not! The "average" rule is a measurement bias. The scientists take the average of the votes in order to determine what is beauty, it's a wrong way. So averaging the votes, gives an average result, which is the average face. Beauty is not that

https://www.youtube.com/watch?v=07MzPrkwJsw