I kept hearing a rattling noise under the hood on my 2019 C7 Corvette at different speeds and RPM so I mounted a camera under the hood aimed it at the belt tensioner area and drove the car. In the video you can see at one point (10 seconds) where the belt pictured at the bottom of the screen vibrates violently and makes a rattle noise. Hope this helps others trying to figure out the noise. The belt tensioners leak oil, go bad, and need to be replaced sometimes.
