The screen used for display must be set to the primary screen not the clone. Use Fn + F7 buttons to swap. I did this with the church display screen and it worked up to the point where I needed to control the computer. My old eyes do not go that far down the pews! Que binoculars! Then I got wise and used Fn+F7 😉
I found the second screen would display the DVD if set to extend windows to this screen (like an extended letterbox).
Another note I found is the common television screen is very low definition. You may raise the definition by using the correct socket and the correct mode on the display. Please read the display unit's instructions about TV&Scart,HDMI or DVI/DVO,Computer settings etc. You will need a way to hear the sound. Not all diplay "things" will act as your sound system. I used my HI-FI. This is due to limitations of the hardware in the large screen TV used as second display or at church the projector only did video.
Some times when plugging around the video I found rebooting (the total cold shutdown and boot from "off" not restart or hibernate) the computer useful. It seems at boot up the video chips talk together before Windows boots up with multiple screens. This can resolve some tedious "I'm not working" tantrums of the computer. Especially if disconnecting the laptop when I left the control screen on the disconnected item...oops silly me!
I have used both a TV and external monitor and also the LCD screen to diplay (3 items connected). Note the computer here a laptop VGN-A517S will only use TWO of the connected screens at once, the third is NOT allowed even when plugged in. I note Fn+F7 will switch around the displays and allow me to choose what two of the three to use. In all cases a seperate audio connection is required. In the case at Church I plugged the audio system into the laptop headphone socket.
