My only complaint about this presentation is the lack of forgetfulness and recovery of old strategies. In a word, it ignores context.

A world with only tit-for-tats effectively becomes a world of always-cooperate once the knowledge that defectors are a thing disappears from visceral collective memory.

And as an inevitable aftermath of that, the world of always-cooperate invites the return of always-cheat. Which invites the arrival of tit-for-tats.

However, the presentation's conclusion remains the same: viable actions in the world we inhabit are largely--but not totally--defined by the contexts that everyone brings to the table. And in most contexts, it pay out more to forgive than to retribute in the long run.