...I find it easier to just slap some black generated media over the video and let the audio run...I place the cut-aways and other visuals over the black media...what I'd like to know is if Vegas is rendering only what it "sees" and not all the underlying layers... TIA...
It only renders what you see. You can prove this by putting a generated graphic as the bottom video layer and cover with any other video. You can tell by the speed of the render to AVI, that it is not generating the lower video track.
I find it easier to just click on the "Ignore event grouping" button, resize the audio or video as needed, and then click the "Ignore event grouping" button again. No extra stuff to clutter up the timeline.