This button is an overall toggle of all Video Output Device
It needs to be enabled in order for Smode to generate any output video.
This toggle is accessible through the [Ctrl]+[Shift]+[Alt]+[W] keyboard shortcut.
The [Ctrl]+[Shift]+[Alt]+[W] shortcut is the solution to make the video output disappear if
creating a Video Output Device
by mistake over the user interface of Smode!
See how to Configure the Video Output
and how to Configure Spout