Before reading the Article I thought it was about injecting special hidden marks in the movies to be able to detect if the movie was pirated, from which copy it

Before reading the Article I thought it was about injecting special hidden marks in the movies to be able to detect if the movie was pirated, from which copy it was pirated. It occurred to me that that may be an interested solution for a problem we have. But I haven't been able to hit the right keywords to do the search. Can anyone give me suggestions on what to look for?