Well you are seeing the heads on Wolfie's side of the stage... another clue on piped in bass..?
The 5150 III has a metalic grill on the front in Ed's stripe configuration and fairly open backs. You can see the silloette of the tubes and transformers inside the heads at about the :39 mark pretty clearly.
But you can also see the heads on Wolf's side are not powered up. There's no red power or stand-by lights lit on Wolf's heads... where all of Ed's side are powered up and the 2 units on the far left you can even see the tubes glowing when the stage goes dark.
I think Wolf was piped into some power head offstage and direct in to the mains. Ed was claerly plugged into the far left stacks and the bottom cabinet was mic'ed as well.