As it's evolving on the Net.
Commentary on art forms (fiction) has been around for a long time. One of the things that delighted me about Chinese novels when I first discovered them was that people added their commentary into the text when copying them. In Western Europe, with the evolution of print, we didn't go that way--commentary developed in separate venues.
Now there's commentary on film and television on DVDs, and some are way better than others at it.
Then there's the Rifleman Harris commentaries, which I think achieves ekphrasis.