HI jeb, You can add the device's ip to about:devices As for the desktop version, I do not have a solution yet.

OK - using win 8.1. First, how do I find the "about:devices" and second, what and where do I find the IP?

I don't know if you can "turn on" this capability for Firefox on Windows.

Personally I just use a long HDMI cable (with a Mini-DisplayPort-to-HDMI adapter) when I need to output to a TV, and use Windows' "projector"-related features. Sometimes it takes a few tries on different HDMI ports. If it needed to be connected full time, it wouldn't be very convenient to have that cable lying on the floor...

There is something called Miracast for Windows 8.1, but it would take a separate adapter. For example:

• http://windows.microsoft.com/en-us/windows-8/project-wireless-screen-miracast
• http://www.howtogeek.com/200897/how-to-use-miracast-screen-mirroring-from-windows-or-android/?PageSpeed=noscript