That's the face of a man who realizes he doomed his species. Chilling.
Ehh. I wouldn't say he doomed the species.
Nuclear Weapons are like this massive, over-arching end game card that a few nations hold in their hands....but I actually feel like, since the MAD-scare 80's shyt ended, that we have considerable bigger fish to fry right now.
Of course, his work has fundamentally changed our capability to kill each other, and he clearly understood that as he showed in the video.