That doesn't sound like good advice. If anything, that behavior would only serve to heighten the tension of the traffic stop not to mention that it would look awkward. Maybe the officer will think you were throwing something out the window like drugs or empty bottles.
Rolling down the window and keeping your hands on the steering wheel seems best. The passenger simply needs to sit still and keep his/her mouth shut. Also, turning the dome light on at night is also good advice. Even though most police cars these days will have a spotlight trained on your car (and you can bet they are recording with a dash cam).
The other poster here saying that you should should answer "no weapons you need to worry about" is unspeakably bad advice. That is almost certain to get you pulled out of the car and unnecessarily lengthen what should be a routine traffic stop. Once you are pulled out of the car, the odds greatly increase that you are probably not getting home for a while.
Sorry, but in my part of the country it is welcomed by law enforcement and taught (at least by some instructors).
Oh, and in North Carolina, if the truth be known, if you have a concealed carry permit then all vehicles in your household are identified as a belonging to a concealed carry permit holder. Law enforcement will ask if you have a weapon. If you are carrying, you put it up on the dash in plain sight.