But they're only "harming privacy" because Google, supposedly, allowed copyright infringement to take place. That's how the law works-- in order to investigate crimes, your privacy is sometimes invaded (when there is due cause).

I'm on your side, though. This philosophy of breaking privacy for investigation doesn't scale with the internet.

This is a civil case though. If my doctor was accused by a patient of overbilling him, would it be acceptable for that patient to peruse (and perhaps leak) my medical records during discovery? No.

But for some reason it's OK for Viacom to see my name on every YouTube link I've ever clicked. Why are some things private and other things not?

If the doctor was accused of negligence, the court would be able to requisition all the medical records of his patients. (Actually this might not be true of a doctor, but in any other industry this would be perfectly legal.)

We're talking about YouTube being the accused, not an individual anonymous user. Am I understanding that right?