It is to enable the testing of plugins and routines before they go live.
Timed Content Plugin
When editing a page in the Visual mode there is an alarm clock in the tool bar, this allows the definition of timed content.
This first phrase is set to stop showing after 6pm 1st May. This can be used to show a demo stream for people to set up their systems.
The second phrase is set to show after 6pm on 2nd May. An example of this can be used to say that the seminar has now ended.
The third phrase will show from 6pm on 1st May to 6pm 2nd May. This will enable the showing of the seminar stream for just the period of the seminar (plus some set up and run out time)
A big plus of this plugin is that the timed content will effectively occupy the same bit of the page as demonstrated by the 3 images that I have used on this page. I think that this will give a professional look to the seminar page as only one video will be on display at a time till the finished message is shown in that space.
Unfortunately the short code uses American date format but as you pick the date from a calendar this should not pose a problem.