For anyone who thinks they may have this sound...
I woke up this morning and drove straight to my SC because I wanted to get this sound addressed. A technician came out and listened to the video, seemed to know exactly what he was hearing, but didn't mention anything. Then we went for a drive together. The second he heard the sound he said "that's your brakes, 100%." Confirmed his suspicion as he kept hearing it.
He said because Teslas barely the friction brakes due to regen, sometimes a coating of rust can build up in cold/damp conditions. I told him I tried doing some hard braking but it didn't help. He said no, it needs to be HARD braking, like going 50-60 then slamming on the brakes just short of the ABS engaging, all the way to a stop. Plus in service mode they can do it with regen disabled which helps a lot. He said he could do it with me in the car but that it's pretty alarming. I told him I'd happily wait at the SC.
So he dropped me back off and he showed me how my rotors looked vs most of the other cars there. He went out and did 10-15 super hard stops. 60 to 0 in like 2-3 seconds. He then put the car on the lift and inspected the brakes, confirmed everything looked fine, and did a minor lubrication of the calipers. He took it out again for 20 minutes and said he didn't hear the sound once. Nor did I on the 10 mile drive home. Was there for two hours total. No charge.
He said it's possible it will come back a little, or may never come back. But it should never need the intense burnishing that he did again. He said if it comes back, I can do a few hard stops on my own, preferably when it's cold so regen is low. Worst case scenario, if it comes back and it's really bad, they could see about replacing my rotors as defective under warranty.
So you may want to try this HARD braking and see if it fixes your sound. He said unless you smell burning brake dust, it's not hard enough.