From the article:
When we went to our seats, the wait staff let us know that despite the fact that the previews were playing, we wouldn’t know until the movie actually started whether we could see the film or not. If it didn’t work, the screen would just turn black. Luckily, the film went through without a hitch.
Not a cinema guy, but assuming those movies are encrypted with modern standards, it is practically impossible if you simply would steal the media. Could be done if you could tap into the original playback device where movie plays and pull decrypted copy out of it.
Edit: As per this AES 128 is used so good luck if you ever stumble upon an encrypted copy.