Reading this. Have to just say something...
Look, the difference between everything that science has been so successful at explaining, and consciousness, is that we know all of science indirectly whereas consciousness is the one thing we know directly. While many properties and processes of consciousness are indeed mostly physical, the fact itself is a different kind of fact than any other fact of which we are aware.
I suppose it may turn out that directness is an irrelevant property, epistemologically. It seems unlikely. It seems rather more likely that the tools that are useful for studying indirectly are completely pointless when trying to study directness, as such tools are themselves a form of indirectness.
This is the distinction the whole zombie debacle is trying to get at.