In a comment a few days ago I mentioned that I was having trouble showing widescreen downloads on the big wide-screen TV, since the Windows screen driver doesn't have a setting for the correct screen ratio. If I viewed them full screen in videolan they were letterboxed for the normal 4:3 screen ratio, so looked fat if I stretched them to full width - and the TV's wide mode for the computer input doesn't have a zoom with vertical expansion.
It turns out that there's a simple fix for this - in Videolan go to settings / video and click on the advanced options, then set the screen pixel aspect ratio to 4:3
This has no effect if you're looking at the video in a window, but if you set it to full screen the picture is stretched vertically to fill the frame - if you then go to widescreen on the TV it has the correct 6:9 ratio.
This ought to work for any wide-screen monitor. Hope it helps someone.