10+ years ago, I bought something at CompUSA which had advertised a $50 rebate. When the store clerk handed me the rebate form, I immediately noticed that it had expired, but was reassured by the clerk AND by store manager that the expiration date had actually been extended, and the rebate would be paid (it was a CompUSA rebate, not a manufacturer's rebate). Of course, that was absolute BS, and the rebate was denied as "expired." So I posted a web page describing my experience, and within a few weeks it came up in the top few search results for "CompUSA rebate" on AltaVista, which was then the most popular search engine. Someone from CompUSA called, and asked me to take the page down; I said no. They offered to give me the $50 if I would take the page down, and I said no. Then they mailed me a $50 check, which I cashed (since they owed me $50 for the promised rebate). Then they mailed me ANOTHER $50 check, which I returned. Then they sent me a $100 check, which I returned. (It was several years before that web page disappeared in a site transition.)

Actually, those notices are there to "educate" the public -- so that when the MPAA sues and you say "Hey, I didn't know it was illegal!", they can respond with "That's why we put that notice saying it's illegal in there."