[Prof.]

So it's the averaged level...So how would one set that level for any given DVD, considering that there are variations in output level between one DVD and another!!?

I'm not saying you're wrong, but I can't see how one would know what the average listening level is for a particular DVD, considering the huge variations in output level..without using an SPL meter all the way through a movie and then averaging the different levels..
And that would apply to that movie only..