I can't see how this is going to work with the AVR doing the switching.
If I run the HDMI cables directly to the TV (bypassing video switching on the AVR), everything works as expected: audio and video being displayed via HDMI from DVR, press the Hub button, DVR gets windowed (still hearing audio), when I run an app or video, DVR audio and video disappear. If I let the AVR handle this, how would the AVR know to stop the DVR audio? The DVR is still sending a signal, it has no idea the TV has switched to a different input.
I supposed having the TV do video switching is a workable solution, but this certainly isn't how I wanted to set things up.