YouTube recently added the offline mode to its YouTube Android app in India and some other countries, but it doesn't allow all the videos to be downloaded for offline mode (for example a video from Google or Windows channel can be downloaded but not from the TED YouTube channel). Any idea why all videos can't be downloaded for the YouTube offline mode?
Google is releasing this feature slowly to individual channels currently. The larger more active channels will get it first. All Vevo and music based ones should be already offline, but they could miss a few non Vevo or Indie ones.