YouTube red was announced a few days ago and promises to add 3 major features to the YouTube experience. The service which consts $10/mo will remove Ads on all videos, enable saving videos offline (unconfirmed if only on mobile) and background play on mobile. These are the same features that were being tested in the YouTube Music Key beta, earlier this year. Creators get a 55% cut of the revenue, which is the same as Ad revenue (and in my opinion WAAAY too high, but YouTube barely makes a profit anyway).
Many people have been critical of this telling other people to use Adblock (which is wrong in my opinion). There have also always been (unofficial) ways to save videos offline, however none of the current methods are build directly into the YouTube client. Background play has (obviously) always existed on desktop, however you can now do this on mobile. The primary use for this is podcasts and music videos (which is a massive part of the YouTube userbase).