Rethinking General Relativity as 5 Dimensions of Physics

Higher dimensions often capture people's imagination, so this is potentially an exciting subject. However the youtube description makes it sound like the author is unaware that this kind of approach has been mainstream for a century (although for all I know they may well have some truly new idea, in which case I assume it'll show up on arxive.org):

Kaluza–Klein theory: "is a classical unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the common 4D of space and time and considered an important precursor to string theory....sent his results to Einstein in 1919[2] and published them in 1921." [0]

As an alternate geometric approach in higher dimensions, it turned out to handle e.g. electromagnetism and Maxwell's equations well, but generalizing it further turned out to be, well, hard, and physicists have been trying ever since.

[0] https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory