Correction! The actual video I was thinking of was this one, also by Mathologer but from 2018: https://youtu.be/ubHVK71F01M https://youtu.be/ubHVK71F01M This

Correction! The actual video I was thinking of was this one, also by Mathologer but from 2018: https://youtu.be/ubHVK71F01M https://youtu.be/ubHVK71F01M This one actually has the geometric (rectangle subdivisions) animations I had in mind.