Very cool, if true

That could be part of it, but even that's extended: I hear him pronouncing "the" as "vee" (0.31) which seems to me to extend the bounds of th-fronting beyond the normal: first that it's an initial th instead of the customary final one (which he also does), and also that it's a voiced v instead of an unvoiced f. Other times his "the" is even harder to parse (0.20), but on other occasions he pronounces "the" normally.

But there's lots more. One is the extraordinary things he does with "r". Most people with trouble pronouncing r render it as something like w, but he doesn't do that. He half-swallows it instead, and then half-unswallows it where it doesn't belong, which is what makes his "island" and "Ireland" identical (see 0.43).

Another particularly odd thing from the beginning is his vowel in "does" (see 0.24). If this is part of the Birmingham dialect, it's much stronger from him than from the sample Andrew provided.

I could hunt through it for more, but that's enough to make the point that this is an accent unlike any I'd ever heard.