"Input Assign" is where you assign the connections on the back to the input you are using, however, I still think you are correct in that it would be a set and forget kind of feature.
I stole "Video Select" right from the manual and it allows you to view video from another source while listening to an audio only source. For example maybe you want to see a Hockey Game on the TV but be hearing audio from an iPod.
I would think it would be set until you change it.
Craig
My wife says I can't do sarcasm. She says I just sound like an a$$hole.