> I then left and the company later got acquired by Level 3 so I don't know exactly how it evolved

It just struck me that there are probably plenty of large media companies that use all sorts of proprietary video streaming products for distribution that we've never heard of, simply because the tech isn't available to consumers.

Media companies are generally pretty secretive about their tech (Netflix being the exception to this rule), so there isn't much to be found about this. The piracy community (because, let's be real here) also won't be interested in a non-free (speech and beer) streaming solutions like these. So that's probably why there is just very little public information available.

But if you use paid digital TV products (Eurosport being a perfect example here) then you are probably already using all sorts of P2P streaming protocols you've never heard of.