A length of time. For a clip, the length of time that it will play, determined by its overall length. Or if the clip has been trimmed, the difference in time between its In point and Out point.
Youtube has the extension Playlist Duration Calculator. How many videos are watched in total for 7 days and the average of 7 days will be shared with users through this tool. YouTube Music statistics will not be included in the data. Reminders for a break can also be created via this menu.