YouTube has announced on its Creators Blog that developers will soon be able to take advantage of a YouTube mobile feature that allows users to download videos for a short time.
This feature will allow viewers to save content to the device for up to 48 hours. But this is simply a way of keeping the viewer connected when an internet connection is lost. Selecting the "add to device" option will mean the video is available for 48 hours from the time the user goes offline. Any longer and it will be lost until reconnected to the internet.
An "on device" section of the YouTube playlist will show everything available without a connection. It sounds a lot like Spotify for mobile, only you're limited to a 48 hour download period. Ideal for travelling though.
Clarity on the exact layout and how many videos can be stored will be provided in November when this new feature launches.