Vloggers want to use best cameras all the time but especially, when you want use back cameras for filming yourself, you really don't need that big screen, so it can go shut while filming.
It can be called "action camera mode" In that mode, you can use your phone as those cameras where there aren't any screens.
After you are filming yourself and want to bring the screen back on, just double (perhaps three) tap it and it opens (it doesn't stop the recording).
This feature is great for battery saving and keep the device little bit more chilled.
