Around 3:38 and after that I see black speakers (I think) in front of the guitar amps.
Are these more monitors? They also have the normal wedge monitors at the front of the stage.
The Who - Sea and Sand (Quadrophenia); Chicago, IL 11.29.12 - YouTube
Looks a lot like foldback for the keyboard players to me. They probably have to take a bit of additional care in stage monitors for The Who, Pete has suffered with painful tinnitus and difficulty with loud sounds, although he seems to be a lot better than he was, but they will worry about the sound getting too loud for him. A band of the level of The Who will have a dedicated foldback mixer, and may provide different mixes for the various players.
Amusing to see Roger still with the standard open shirt. And just brilliant they still tour.