One of the curious things about YouTube Music Key in its initial, beta form was the way that while it enabled subscribers to cache songs on their smartphones, they had to download the full videos rather than just the audio. This, it seems, may be changing.
Android Police has been digging through the source code of the latest update to the YouTube Android app, and has found a hint that an offline audio-only feature is coming. Specifically, where the previous app’s code listed strings for 360p and 720p video quality for offline storage, the new version lists an “Audio Only” option. Such a change would be a logical one for YouTube Music Key, given the larger file-size of videos (particularly at 720p quality, which is HD).