Playing a copy of Alien shouldn't be this hard. I'm a GNU/Linux 
user, and I find the experience of playing a blueray atrocious. First, 
I must rip the movie with MakeMKV (which is non-free), which produces a 
decrypted folder structure. In this folder structure is a directory 
called STREAM, where M2TS movie files are located.
     I found that Alien didn't put the whole movie in an M2TS file 
(like almost all other bluerays do), instead chunking it up into 
multiple ones. They are named out-of-order, so I needed to find the 
appropriate PLAYLIST file. There were many, but I put `strings` on all 
of them, and slowly reduced the number by searching for known 
STREAM-title numbers (like 00938 in 00938.M2TS). I deduced it to two, 
then took those title numbers and ran them through `ffmpeg -i 
"concat:etc" ...` to produce a final movie.
     Through this inlining process, my ramdisk isn't big enough to hold 
the output, so I have to read and write to my NAS. This takes about 
four-times as long.
     I also found this neat link:
https://en.wikibooks.org/wiki/User:Bdinfo/mpls