Saw this on Reddit yesterday, absolutely great work!
Where on Reddit did you see this?
It was on the front page yesterday
ReadMe has had something similar for quite a long time: https://dash.readme.io/login
The CodePen example is a bit more impressive in that it doesn't use any pre-rendered frames for the animation.
+50 Medium claps o_O
Very cool :) Reminded me of the excellent Basecamp sign up form a few years ago, with the guy's hand pointing each input http://media.konigi.com/interface/basecamp-form-focus-2.png