What event lead to the movies putting the FBI warning on almost all movies now?When did it become a crime?

People have always "bootlegged" stuff since they learned how to hook up 2 VCRs to the same TV... they put that on there to scare people mostly. I'm not sure if it was any one incident, but it's just a lot of people doing it all the time, they will never stop it though, they would probably save some money by leaving them off, most everyone knows all of that, it is subliminally burned into our brains...