After spending about 45 minutes trying to figure out why the optical drive (ASUS BW-16D1HT) I installed in my new computer build was not being seen by Ubuntu 18.04, a post at AskUbuntu (I did not save the link) mentioned that the optical drive should be installed in the first SATA slot (ID 0 [zero]). After I did that, and rebooted, it worked fine:
- insert a DVD or Blu-Ray disc, and the Nautilus file manager mounts it automatically
- open VLC, and select the drive (now correctly known as /dev/cdrom or some similar friendly name), and it see the DVD properly and can play it
Regarding playing DVDs: you need to install VLC, and a bunch of codecs, typically in a “restricted” repo. Here is the official documentation -- no need to add third-party repos.
sudo apt install libdvd-pkg && sudo dpkg-reconfigure libdvd-pkg
You will also want to use "sudo apt install vlc" to install VLC. For some reason, installing using the graphical Software marketplace app gives you a slightly older version.
sudo apt install vlc
If you want (or need) to set your device region code:
sudo apt install regionset && sudo regionset
You may need to specify a device to regionset, e.g. /dev/cdrom