full screen app

I have a requirement where I would need to cast a feed from a video camera overlaid on a video file. The challenge we face is, every time this should not be previewed, using a hotkey this should be made to full screen. I plan to use a USB based push-button and configure the hotkey. Let me know...

Have a full screen application that I am trying to view as an OBS source. I have tried Window, Screen, and Display Capture. When I tried display capture it shows nothing. When I try window is shows some options but not the application I am trying to broadcast, and nothing in display...