That was really good, I'll keep an eye on him, thanks for the link!

Although note (didn't think to say this last night) that the video is no way contradictory to the idea of a security budget, or the consequences that fall out from reduced block reward. It is, instead, a graphical representation of how to visualize the dynamics of it -- in this case, it would move one of the curves to the right, as he describes; less existing mining capacity becomes profitable, and the area that can be mustered for an attack (those rectangles he draws) gets bigger.

Nothing really new there, unless I missed something. Just a formalization of game theory dynamics, which has been discussed many times by many people. Still, a nice visualization, and I always get excited when smart and thoughtful people explain things precisely, vs the usual suspects.

So when the reward is low and there are a tonne of unused ASICS and the cost of attack is low enough a 50% attack might be successful. That will depend of the slope of the curve though.