On most websites when opening a video to fullscreen a prompt drops down from the top of the screen that shows a white lock, and says the video is now fullscreen, press ESC to exit. The playback controls autohide but when i mouse to the bottom they appear and I can navigate, pause, play, etc.

Now recently on some websites when I click to fullscreen a video, the same prompt appears but this time the white lock has a red slash across it, and once that prompt goes away, nothing will appear, no controls show up when moving the mouse or clicking, and the only way I can get out is escape. How can I get it to go back to the other way?