I agree that even if talk of your work goes on beyond the particular shots, it should be quite acceptable, even welcome, to take up otherwise dead air where you didn't make any changes with further explanation.

Poita, are you saying you'd take audio of him talking about all of his work and then edit/arrange that into a topical commentary track? If so, I could see it being interesting, though I do enjoy the flow of a real time talk; but then I may just love the occasional mild rambling and accidental insight that tends to slip in...