Weighted flies on a dropper rig? Had some success with those bass fishing years back. A single hand 8wt rod and a 'bit ch' to cast along brush lines. But it worked ... just bring lots of extra flies ... you'll need them.Please don't take offense but why would you do that?
I'm thinking he might be using a full super fast sinking line with a buoyant fly, just keeping it off the bottom. But I don't know for sure.