With digital projection, I've read that movies can come on disc or even be streamed over a secure line.
So I doubt its the typical bluray player...but still, if it WAS just a player like that, I'd be like, here, play this disc instead, which would be Harmy's Despecialized edition. Theater would NEVER do it though.
Back in 2002 when I worked at the theater, with all real film projectors and music that played in the lobby and theaters not showing a movie at the moment that played off a cd. (I've probably told the story before) Since most all the music was really bad music of those early 2000s, I was able to get the cd, copy it, (it was just one long track all mixed together) cut out the real songs on an audio editor and keep the ads, then pick a bunch of music I wanted to hear and then made an hour long mix. Even had a friend make a label that looked close to the original. Had a projectionist put it back in the player....and yeah, a whole month of better songs. A few movie themes, some 60s music, electronic style songs, even a few video game remixes that were a bit hard to tell. One really nerdy guy that wasn't in on it was like, is that Megaman 2 Airman stage remixed? Were all like, no, we have no idea what you're talking about.
Some manangers were even like, theres NO way thats the real cd, but whatever. They weren't going to find out or say anything.
I found out, that had one of the corporate people from the theater, or someone who was high up in that area that got the music on those real cds had shown up to our theater and heard a fake soundtrack, the theater would have probably been in some big trouble....lol. Oh well, been 21 years later, so all good.