I usually get very angry at the excessive use of animations everywhere, so I expected that this would give me a nice hit of righteous indignation to top off my afternoon. But this is a fantastic use of animation. In a UI like this, animation is great to helpfully draw your attention to where it’s needed and give you some indication of why you should look there. Very nicely done!

Why not put these in the HTML instead of as videos?

I've doing the exact same thing with https://motioncanvas.io/

edit: this is the actively maintained fork https://canvascommons.io/