What could be causing this noise?

 

Sounds normal to me, there is a natural resonance to the intake system at idle. Your video is of the driver side not passenger side. Is the noise just at idle or do you hear it while driving at different rpms and with the car moving ? Not enough info provided to assist.

 

My bad I meant to put drivers side. Noise started this morning, doesn't happen at start up but after driving it for a while you can hear the "huuuuu" ever so slightly. It starts at low speeds first/neutral braking. It goes away when the gas is pressed.

 

Its intake resonance.

Did you recently do something to the intake?

Taking off the intake lid makes it way louder.

 

Nothing, everything in there is stock.

 

Its most likely just the intake humming like normal.

Try this...wait for the car to idle normally. Then pop the hood and remove the airbox lid while the car is still running.

You'll hear the noise get louder when you do that.

At least use that test to identify the noise.

Could also be this?