The key change: YouTube “partners” — video owners who make money from ads on their YouTube clips — will need to let YouTube put their clips in the ad-free service, too.
If they don’t, YouTube will make it nearly impossible for a casual visitor to find the videos. It will classify the clips as “private,” which means the only people who can see them will be those preselected by the video owner.
via YouTube Pushes Video Owners to Join Paid Subscription Service | Re/code.