It means Cam is saying some crazy and illogical, or else mean, things, and he's just not paying attention to how crazy or mean it sounds. You know how when some people are upset, they start to say all kinds of things that don't make any sense, or that are cruel. You could say to a person like that, "You're not hearing yourself! Do you hear what you're saying? You shouldn't be saying things like that!" Hope this makes sense!

In the context of one person complaining to another, "you're not hearing yourself" probably means that the person listening to the other person complaining is trying to point out that they're saying something ridiculous, and to ask them to reflect on their own words and realize how foolish they sound.

The answers above are correct. However, it might have been more accurate for the actor to say: "You're not listening to yourself." "Hearing" is just a matter of perceiving the sounds. "Listening" is a more sophisticated process of interpreting those sounds into ideas (which, in this case, are probably illogical) Perhaps "hearing" was chosen to imply a problem even more fundamental than a lack of listening.

The others have explained it. We have a similar expression... "Just listen to yourself!"