Given the scale and metrics involved, seems pretty nominal. Maybe not free, but for the context might as well be. Something that could be highly automated if it were transparent and fair.
I work in the space... that level of visibility is a trade secret because it exposes contracts like isp hosting costs... it's also hard to calculate... and it's definitely non-trivial.
it's not going to be exposed because why show your cards, you're not a CDN. And there's a reason people use YouTube not CDNs and it's not just the complexity and discovery, it's still not super cheap.
