I thought you guys should hear it for yourself.
Wow! Those brakes sing! Like I have said previously mine would squeal a little when used lightly for the life of the OEM pads.. about 20k miles. It was worse on hot days.. but as has been recommended here.. cleaning made the noise go away for a while. On mine, I would blow out the dust or use brake cleaner, but the noise would come back. I found if I would brake harder and get some heat on them... basically knock down the glaze.. they were quiet the rest of my ride. Really, it only made noise for a few miles or on short trips, then went away.
Your brakes are efft! That is clearly harmonic vibration. It happens when the pads and rotors are glazed, and a harmonic vibration creates a loud audible tone.. much like a wet finger around the rim of a crystal wine glass. In your case there could be a defect in one or both rotors.. but I have a different possibility to propose. It just occurred to me what the problem could be, and if it turns out I am right, you owe me a beer.
If one of your calipers is not functioning with as much force as the other, or, only one side of that caliper is pressing its pad against the rotor, harmonic vibrations would not be counter acted by equal pressure applied on both sides of the rotor. In fact, I think that is what it is. You have a bad caliper, or air in the line, or perhaps a caliper piston is binding. It may only take one of the four pistons to not be pressing as hard to make the noise. You state that the harder you press the worse it gets.. well if one side of the caliper is jact then all it does is force the rotor hard to the malfunctioning side, and it would sing loud, just like it does. Of course, this would be easy enough to check with all the pads out and very light application of the brake lever. You would need to be very careful not to pop the pistons right out. Probably best to only test one side at a time leaving the other side on the rotor with pads installed.
I might be wrong, but your sh!t is definitely jact! It's not the normal brake squeal we have had reported on the 9ers with brake noise. When mine made noise is was a high pitched ringing.. way higher pitch than what yours are making... and hard application of the brakes made it instantly vanish.. assuming I was going fast enough to brake harder.. that was the frustrating part.
Second, the "heat treatment" of the rotors performed by your dealer is crap. Obviously I am not the first to say this and I am sure you knew it was crap when the dude squatted down and left it steamin' in front of you.
That said, the 9er rotors cool almost instantly under normal use.. so I doubt if your idiot mechanic heated them by riding the bike, he could hurt them with cold water. If he put heat to them with a torch, that is just stupid and they would likely show signs of this by having scorched paint and wisps of carbon dust covering them. The notion that heating them and quickly cooling them with cold water can somehow alter the temper of the steel is absurd. They would have to be heated glowing red a$$ed hot.. almost to the melting point, to change the molecular alignment. I would not worry about this shop being able to do that. What could happen if they were heat red hot, and heated unevenly or rapidly cooled unevenly, they could crack.. again, very unlikely the shop possesses the means to even come close to this kind of heat. So check for burning or blistering paint and carbon on them, otherwise blow it off as just stupid idiot crapping out piles of worthless lip service in your direction.
Check the operation of your calipers!