The problem with streaming music through YouTube has always been the fact that you have to stream an entire video, rather than just an audio track, which means you’re consuming a lot more data. This problem is more noticeable on mobile devices, especially for YouTube Music Key users that download videos to their smartphone for offline playback. Fortunately, there may be a new feature rolling out in the new future that will allow users to download just the audio track of a video for offline playback.