Let's figure out why our pianos are the way they are. And surprisingly, it's all maths!
The "history" by Formant who inspired this video:    • The Mathematical Problem with Music, ...  
While the intro is similar, I thought I'd give a few more insights into the intricacies of the equal temperament system, so here we are.

0:00 Intro
1:00 Just Intonation
6:00 Any Tone Equal Temperament
9:00 The Big Bad Table
12:12 Best Tuning = Your Tuning

Shoutout to the awesome #manim community for making such videos possible!