I feel like the Manim[1] library Grant created to make these videos is becoming some sort of "video matplotlib". I've seen it used in so many maths videos up to this point. There seems like a good amount of value in creating a simple, structured and clear way to represent these concepts in videos.
I never knew he made a whole open source project for it, nor that it was even a library doing the animation. I thought he hand-animated his videos. Brilliant.
What made his videos catch my eye was the plotting of the vector text fonts, I love that effect. I'm pretty sure he used the Hershey fonts in early videos.
[1] https://www.manim.community/