Pirating anything such as software, movies, music, video games etc is neutral karma in the sense of good/bad.
Despite what people and our laws may say pirating i.e making a copy of something is NOT stealing, so in the moral/ethical restraints of vinaya/precepts you are not breaking any vow or precept.
Buddha did not lay down an ethical constraint of not copying something, if so when you look or take a picture of a person you would "steal" their image! or we could internet search for an image of the mona lisa and find countless "priceless fine art thieves"
Buddha laid down an ethical restriction of taking physical belongings that are claimed and belong to others. This is not the case when one pirates a song or a movie.
Now if you stole the source code of a video game, or the original recording of a song or movie now that IS stealing.
Pirating movies, music, games etc is just making a copy of an immaterial phenomena, the original material recording still belongs to the author.
For those people downvoting this actual logical comment as if my opinion and logic is invalid I point you to THIS thread, where Yuttadhammo explains the actual implications of the concept on more depth.