There are 2 types of digital fingerprint - one is in the picture and the other is in the soundtrack. One benefit of digital projection is that the image can be subtley altered on the fly by the projection systems. By introducting a very minimal amount of noise into the image and soundtrack it is possible to encode it with information relating to where/when the movie is being projected. In this way it is possible to take even a very poor quality pirated movie and trace where the piracy took place. It is then possible to follow up with the cinema in order to help prevent future piracy. In some cases cinemas have faced not being able to show content unless piracy issues are immediately dealt with. It is not unusual for the soundtrack and picture to be sourced from different cinemas.
It is possible to trade high quality pirated movies illegally internationally. In this way by pirating one movie well it can be possible to obtain many more good copies and to profit through selling copies of many illegal movies, often taking advantage of the window between when a movie is released in cinemas and when it is released for viewing at home?
Yes - cinemas trade on the high profile of a movie when it is first released, and before it appears for viewing in the home. Anything that impacts attendance at cinemas hurts them, and being able to watch a movie at home instead of in the cinema might cost a cinema a movie ticket, as well as losing sales at the concessions stand. In addition to this the DVD sales of a movie are a huge contributor to movie profitability and so help to justify movie production costs. If the DVD sales are impacted then movie budgets are cut - this can mean fewer movies, as well as movies with lower budgets.