Again it's not a traditional video file. Iirc its a series of really high quality unconpressed images being played back at once with audio. The max resolution is is 4k but even the 1080p films can be 100gb. The real knee slapper is when the video's resolution is 4k but the projector is old so it can only output max 1080p.
The movie at a cinema isn't a regular mp4 file, it's a massive 100-300gb proprietary file that needs a valid license key to even be played back during a specific time period. Good luck decrypting the file or getting the company that issues the keys to the cinemas to give you a key because you're not getting it to play early. Iirc somehow the Korean rip of the Sonic the Hedgehog movie was leaked early and something similar happened with the My Little Pony movie, but those fan bases are incredibly autistic and will find a way.
I do not remember the name, but there was one being developed and the UI was made with QT. I don't know if it used it's own method to download games or was just a GUI for steamcmd.
Yeah modern Bungie is not great.