Recent YouTube app upgrade brought improved search results and tabbed channel, but inside the app there were some interesting features hidden. Thanks to an AndroidPolice teardown, the hidden features point out to a streaming music service and offline video playback.
The hidden code points out to a Music Pass feature that would let users listen millions of songs with ad-free. An addition to that, there would be an option to pin content to a device for offline listening, but it wouldn't last long as it has specific time when it can be listened. Of course, this doesn't mean YouTube will launch these features to the public.