Also makes it look like the USA has a serious fat left extremist problem, which is the opposite of the truth.

I haven't watched it yet either. But from looking at it I would assume is making a point about, how when you look at it. In terms of distances in 2d space. And not distances along an arbitrary curve. The far right and centrists are closer to each other. Which in the US is definitely the case. Especially considering our far left is solidly economically right wing.

The problem is that so called centrists aren't ideologically centrist. But reactionarily centrist. They don't have a guiding belief or principle beyond finding and occupying any imagined center they can. Even where no center exists.