I’m new to the Cooper world and acquired a 2008 Cooper s with the turbo, it’s giving me a p1497 code, downstream throttle air leak, can someone confirm if this hissing is normal, sounds like it’s coming from behind the motor/ intake area

 

Of course it won’t let me attach the video

 

If it's making a hissing sound, and you've already checked for snakes under the hood, I would guess that you do actually have a air leak after the Mass Air Flow sensor. Check the tube from the air inlet just behind the grille area and leads to the back of the motor. See part #10 in this diagram (RealOEM.com - Online BMW Parts Catalog). Also make sure the housing for the air filter is securely closed.

Good luck!