To learn more about various areas of Group Theory: https://en.wikipedia.org/wiki/Group_theory
Galois Theory article in Encyclopedia of Mathematics: https://encyclopediaofmath.org/wiki/Galois_theory.
[Note: as it has been correctly pointed out by MasterHigure, the dials at 8:10 should have 4 and 6 edges (as opposed to 5 and 7, respectively). That is because of each of the factor polynomials being reducible and having 1 as a common root.]
Some ideas in this video where inspired by Dan Goodman’s article “An Introduction to Galois Theory”: https://nrich.maths.org/1422.
The “trousers” metaphor was based on similar analogy provided by Eric Weinstein in one of Lex Friedman’s podcasts. (This and many other interesting episodes can be found at: https://www.youtube.com/c/lexfridman/)
To learn more about mathematicians that made a substantial contribution to Galois Theory:
Evariste Galois (https://en.wikipedia.org/wiki/%C3%89variste_Galois)
Niels Abel (https://en.wikipedia.org/wiki/Niels_Henrik_Abel)
Joseph-Lois Lagrange (https://en.wikipedia.org/wiki/Joseph-Louis_Lagrange)
Paolo Ruffini (https://en.wikipedia.org/wiki/Paolo_Ruffini)
Do not stop exploring!