The math background needed to enjoy the video is not very extensive. Grant Sanderson (3blue1brown) explains everything to the best of his ability from a perspective of “discovering mathematics” and helping you “convince yourself” that you could have come to the same conclusion as well (i.e. grasping as much of the proof as you can). And if that goes over your head, then the animations are still really pretty!

My description:

An intreguing video that takes an innocuous problem of finding an inscribed square in a closed, continuous curve and connects it to familiar topologic objects, like the torus (or the coffee mug!), the Möbius strip, and the Klein bottle.

Timestamps:

0:00​ - Inscribed squares

1:00​ - Preface to the second edition

3:04​ - The main surface

10:47​ - The secret surface

16:45​ - Klein bottles

22:38​ - Why are squares harder?

25:10​ - What is topology?