Oh Ok I see. It appears (from the dearth of quoted text on the linked article) that they are running both a tracker _and_ a seed. The seeder is for their customers only, because then they don't have to pay for upstream access. The p2p connections stay within their network. They don't want to seed normally because they don't want to connect with non-customers, and being choosy like that would make them appear to be a bad peer. So they use this second tracker to inform their customers of this special seeder and of each other. Sounds like a win-win to me.