Although I’d like to see this as well I would also like to know if this technique offers any advantages over a stopped housing dado which I think are a lot simpler to make.
I think the advantage might be that the joint doesn’t rely on glue, because it is an interlocking joint. I am sure Paul will address this technique somewhere in the future, but for now it’s beyond the basics as far as I know. Don’t get me wrong, I also like to see him making a sliding dovetail.
I would also be very interested in seeing this, since I’m building a cabinet with a divider installed by sliding dovetail. Although it’s not Paul, Roy Underhill presents a tapered sliding dovetail in some detail in this episode: http://www.pbs.org/woodwrightsshop/video/3000/3008.html. I followed his directions and the 2nd and 3rd ones came out quite well.