Whistling for no reason

Are you referring to the warning buzzer?

Is that a check engine lit up on the instrument cluster?

It is hard to tell just by the noise. Perhaps if there was also a warning light to go along with it, but then again you would probably already know it then. Is perhaps the warning light out? Turn off the engine, then turn the key just to run and see if all the lights come on for bulb check and post another video showing all the lights on the instrument cluster coming on for bulb check.
If you still cannot figure it out, perhaps removing the fuses or relays know to be for the warning buzzers to try to narrow it down to which then see what is wrong and why it is making the noise and if also the bulb is burned out or what. If you have not already done so, try buckling the seat belt, try tightening the gas cap, stuff like that, too.

Is this a hybrid?