I watched the new video soon after it came out. But I haven't been able to post about it until now because my jaw, having dropped to the floor, has been in the way of the keyboard.
I still can't say much; I'd just be injecting a long string of superlative adjectives into a sentence: amazing, beautiful, remarkable, effective, aesthetic, practical, elegant, glorious, well-conceived, phenomenal, etc., etc.
But I will say this. The first game I designed and wrote was a (Newtonian) multiplayer space combat game for the IBM mainframe. Since then I've been designing games, active (as a amateur) in game development circles, and programming (non-games) and managing some very good developers in my professional life. I've even written my own galaxy exploration game (probably never to be finished or released).
So I'm in a certain position to say that what Josh has shown in this latest video is well-deserving of all those adjectives I listed above, and a lot more besides. It's remarkable work, done remarkably quickly, and Josh deserves every bit of the awe being heaped on his efforts.
There's an old saying about building things: you can have it fast, you can have it cheap, or you have it good -- pick any two.
Somehow Josh seems to have found a way to do all three.