I have an installation with 4 tv's connected to an a HDMI hub and this hub is connected as second display in a windows 10 computer.
All is working nice, but all tv's are far away from the computer, so when we expand the desktop to play some video (VLC, youtube etc...) we have to fish with the mouse to find the opened window to bring it back to main desktop and change what is being played.
Actually we make a workaround turning off desktop expansion and changing video, but I was guessing:
There is some way to preview in the main screen what is being displayed in second one?