try putting a very thin piece of aluminum foil in ultrasonic cleaner - like the type used for ribbon mics. Give it 30 seconds, and when you take it up, you'll notice it has turned translucent. Look closely, and there's literally thousands of very-small holes punched in the foil.
ultrasonic cleaning works by cavitation, that is, zero-pressure "negative" bubbles collapsing and exploding, giving local scrubbing action
TL:DR - ..don't use for anything you wouldn't clean with a toothbrush..
As for Dan's method - was it almost anyone else, I'd be worried. But if that guy tells you he gets consistent good results like this, I'd have no problem trusting him. He, if anyone, has been around for a while

/Jakob E.