This whole thing is kind of a joke to me. Seems like an invasion of privacy to me. However, I agree that Viacom has every right to demand any of their products be removed from Google. And perhaps the right to know who is uploading the copywritten material. But obtaining a list of IP addresses for everyone who ever viewed any of that material is crap.
Not every IP address logged necessarily tells of a person who sat and watched a full length movie. All you have to do is click on a link, and the videos typically auto-start. You could then immediately click another video link and have never actually even viewed the material.
This opens up a huge can of worms for online privacy rights. Now any website you visit that records IP addresses, can be ordered to give out any/all information on their user's IP identities without a warrant being issued for such a search in regards to each individual person. Therefore, companies, or even the government perhaps, could order Google to give up IP information on anyone who ever searched for "XYZ" and then use that IP address to identify a person's location, without ever being issued a warrant for that person.
Take things like this, and throw in the "Patriot Act", and good ole Uncle Sam (Bush Administration) can do whatever they want. Won't be long before judges start allowing every constitutional right to be shredded apart.