By “South African” I mean the accent of native English speakers, which is what he was imitating, not the Afrikaans, Venda, Xhosa, Tswana etc whose second language is English. If you mean variation within SA, there are slight regional variations between the four provinces, but comparatively little within the provinces, apart from obvious dialect groups such as Cape Coloured (or whatever the PC term is now), whose first language is usually Afrikaans anyway. I imagine this is similar to Australia - or not? I’d be interested to hear.
Contrast this with the accents in the UK, which vary even from one side of town to another.