While it deserves a hearing, I personally find Dennett's argument here to be weak sauce and, like many of his "new atheist" bretheren, Dennett seems to be very busy building and burning straw men, missing the forest for the trees and refuting assertions no one of note from the other side is making. I find the magician's slight of hand metaphor to be a more apt descriptor of his alleged chain of logic and what he proports to be able to demonstrate. Nevertheless, this is the sort of somewhat ridiculous tautology (There is no consciousness because consciousness doesn't exist / I don't have to explain consciousness because we are not really conscious) that must be faced and challenged for anything outside the dominant paradigm to get a fair hearing.
For me, the more compelling arguments for the materialists resort to the evidence that there are specific brain structures that correspond to every aspect of human consciousness - and that altering, injuring and/or destroying these structures have entirely predictable affects on specific functions and qualities of consciousness. V.S. Ramachandran's talk is a good example of the sort of survey that might immediately lead one (though it is important to note that Ramachandran is not making this assertion nor denying it here) to the conclusion that if the phenomenon under consideration is altered or stopped when a physical structure is altered, injured or destroyed that the latter must be the necessary cause or source of the former. That is the natural assumption with the following associations between specific phenomena of consciousness and their corresponding brain structures: