Watch Later tool
You will automatically have a playlist for your account called 'Watch Later'. This Playlist can be used immediately and allows you to add videos you wish to watch, but do not have time to there and then.
To add videos to your Watch Later playlist simply click on the ‘Watch Later’ icon where ever you see the video listed.
The 'Watch Now' playlist works dynamically, meaning when you’ve viewed a video from the list it is automatically removed.