I'm rather surprised that it appears to me that an upper-tier DVD player seems to require the user to manually adjust 4:3 vs. widescreen images.
My old, relatively inexpensive DVD player output signal, and my HDTV would auto detect if it was 4:3 content or 16:9 content. That way, when I watched the Honeymooners, Ralph looked appropriately fat, because the DVD player output video in its appropriate aspect ratio by default. If I wanted to stretch the 4:3 image to fill up the screen in some way, the TV offers several options, but by default, 4:3 stays 4:3, and 16:9 stays 16:9.
The Denon doesn't appear to allow that, if I understand it - it spits all content out at either 16:9 or 4:3. So if I leave squeeze off, it'll stretch 4:3 content to 16:9. If I turn it on, it squeezes 16:9 content to 4:3. The HDTV, naturally, sees it as the Denon outputs it and keeps it that way. So now poor Ralph Kramden ends up even fatter than he was, or my widescreen images get squished (depending on if Squeeze is on or off).
Is there any way to set up the Denon 3910 to output 4:3 content "squeezed" so that it is actually displayed in 4:3 - but leave 16:9 content alone? I have a hard time believing such a feature would be left out, since cheaper players can do it, but I've not found such an option in the manual or by experimentation.