I have installed libdvdcss2, but I still get this error when trying to play DVDs:

libdvdread4 was installed by default (This is a new System76 Pangolin Performance). I ran the install-css.sh script, and it completed with no problems.
I can confirm that libdvdread4 and libdvdcss2 are installed:
mac9416@charlotte:~$ dpkg -l | grep dvdcss
ii  libdvdcss2                                 1.2.12-0.0medibuntu1                    Simple foundation for reading DVDs - runtime libraries
mac9416@charlotte:~$ dpkg -l | grep dvdread
ii  libdvdread4                                4.2.0-1ubuntu3                          library for reading DVDs
 
     
     
     
    