If one watches the entire "Fly Fishing 101" segment of the video, nymphs are mentioned numerous times and not in a derogatory sense. It is simply stated that all the fish caught on the video were on dry flies. I think this was the right approach for the purpose of this particular production. If someone can successfully introduce a child or grandchild to fishing challenging park waters with an invisible nymph (bobbers are not a good idea) versus a bright looking, nicely dressed dry, I'd like to know how. After all, how many video gamemakers choose tiny, drab colored creatures clinging to a streambed as the superhero? Instead a number of the characters (both the good- and the bad guys) are endowed with gravity defying abilities and more.
It is pretty clear to me James is not personally adverse to fishing nymphs as evidenced by this article he wrote for the 2012 Troutfest Journal:
Also, check out http://www.flyfishingsmokymountains.com/flies2.html