I'll give you one reason. I've never done any front-end stuff before. But maybe a month ago, I got curious. Perhaps because I read HN everyday.

And if you try to immerse yourself in the front-end world, you get 'yeah, learn HTML/CSS/JS, BUT, also learn Angular, React, JQuery, et. al...' It's good to get a reminder that Javascript in and of itself is a capable language. I'm sure I'm not the only one in this camp.

Maybe it didn't need to be 12 minutes, and it was certainly more of an 'oh, interesting' than anything, but I'm glad I took the time to watch it.