For those saying Constantine should have been on HBO, Showtime or Cinemax it couldn't be, not any more, Hellblazer from Vertigo could have been on a premium network because it was a mature themed comic but once DC shifted him to the mainstream DC universe he could no longer be a mature title. Once he was made age appropriate they couldn't risk having a separate mature version on tv, the brand has to be universal across media especially if the Justice League Dark movie happens.
As for the ratings I'm pretty sure they only count live views, they tally streaming and dvr but I don't think those numbers are as big an influence because they don't make as much ad revenue off them (networks hate dvr's and streaming, they want you locked to the outdated box). If you watch a show on amazon, netflix or hulu they are either ad-free or have few ad's and the network doesn't make money off them they only make money if the streaming service pays a license fee I believe. On network web sites they have fewer ad's as well and the revenue those pull in probably only pays for the costs of the actual streaming and misc costs of putting them online so most of the money is probably just coming from live ad's, international licensing fees and eventually dvd/blu-ray sales.