I think I understand question 4 after some time. What helped was ignoring the "no statistical evidence is provided to show" and looking just at "humans act selfishly MORE often than they act unselfishly." That second claim is now, like the video said, straight forward. The part that tripped me up initially was the claim that there wasn't evidence of this. Thinking of the evidence part AFTER the fact is the only way I was able to see the "winner" as humans act selfishly more often.