This feature will allow you to limit your video to only one view per viewer. That means if they watch any part of a video and then close the browser tab or window and then come back to it, the player will not play the video.
This is done via a cookie. So if the viewer deletes their browser cookies or uses another browser or machine the video will work again.
You can find it by navigating to Playback Options:
Just turn the toggle on and save your settings. Once a viewer plays the video once and then tries again, they will receive this notification: