If it was some kind of crackling sound then I assume it would be the engine cooling down, but that sounds like a struggling computer. Best to bring it to the dealership and show them the video if needed.
I don't have my Atlas yet, but I know that my '16 GTI will sometimes, but not always, make noises like that after shut down for about 20 seconds. I'd guess that it's performing system checks after so many cycles.
That is a possible explanation, recently read about someone hearing sounds from the dash after the car has been turned off and it was just the vehicle checking all the components. Probably more prominent with how complicated cars are getting.