The following papers represent I think a pretty good summary of his response to the sort of objection you raise. They might not be the best, but they seem to be the ones that come to mind at least for me.
https://ase.tufts.edu/cogstud/dennett/papers/quinqual.htm
https://ase.tufts.edu/cogstud/dennett/papers/JCSarticle.pdf
The first is an extensive attack on the notion of qualia as a useful notion. The second explains the methodological approach implicit to rejecting this sort of notion, especially in the social/psychological sciences.
>What are qualia, exactly?
Sets of associated ideas? For example, a door knob might be associated with (1) wood, (2) black, (3) grasping, (4) turning, (5) my right hand. All these ideas are activated to some degree when I contemplate the door knob, and to a greater degree when I contemplate myself contemplating the door knob.
Hawkins posited in "On Intelligence" that consciousness is simply the feeling of having a neo-cortex.
While I am as baffled as any/many at having subjective qualia appear so "real", I really don't have any basis for believing/thinking that they could arise from anything else other than from physical quanta hitting my senso-sphere and being interpreted by a biological machine.
I also have no basis for not thinking/believing that this is not nonsense.
How you you break the conundrem of primary-physics vs primary-mind?
Appear so real compared to what?
Are you claiming that your experience of your own thoughts are subjectively more real than your experience of your sensory perceptions?
I think that most of us can remember being 'nothing' (this might be wrong), and it baffles me why people are afraid to die, which is simply returning to 'nothing'.
EDIT: If you are a physicalist. Some people are not.
EDIT2: "The Truth" has nothing to do with whether one is a physicalist or not, but the interpretation of some various sub-sets of the facts inform various ... schools of thought.
(honest) why is this a problem? what's the difference between my "experience" and the experience of, say, a film camera?
Likewise, I could say there is no difference between my experience of satiation after eating, and the experience of a garbage can being filled full. If you don't think there's a problem with that, fine. No way to show there isn't. However, people inclined to agree with your film example might not be inclined to agree with my satiation example.
Is there any difference between light falling in your eyes and your experience of vision, and light falling in a corpses eyes, and its experience of vision? Does a corpse experience vision as much as you do?
One would argue that there's more chemistry going on in neurons feeding to the optic center, but I'm not well versed in neuroscience to tell you where the signal stops.
What is the implication for the conscious experience of the camera?
Sure, but we're gonna limit ourselves to neurons and the degree of connectivity between them. A camera has none, QED. The more challenging comparison is between a comatose patient and one with locked-in syndrome: https://en.wikipedia.org/wiki/Locked-in_syndrome. There, we can't exactly come up with some 'an agent capable of sensing the world, and responding to changes in its environment' that an outside observer might use.
For example, he insists that our consciousness isn’t quite as broad as we think, and presents ample evidence to show the we are aware of much less than we think we are. Great, but totally irrelevant for explaining the fundamental phenomenom of subjective experience. And yet it is presented as evidence that the phenomenon is really not a problem at all.
What makes this even more frustrating is that the existence of subjective experience is really the only thing one can be absolutely sure of in this world (see Descartes and also the brain in a vat thought experiment). And yet it is the one thing that Dennett refuses to acknowledge.