He mentions the responsive design being really hard, and that was something I couldn't quite articulate to myself when I saw that talk a while ago... the ideas

He mentions the responsive design being really hard, and that was something I couldn't quite articulate to myself when I saw that talk a while ago... the ideas Bret Victor presented, only a handful of them are general purpose. I don't see how one could develop the timing examples he had, for instance, in a way that makes sense outside of his specific work on his 2D platform game.