You CAN watch DVDs with Ventura, but you need a Mac with a DVD / Blu-ray player / burner. Ventura comes with Apples, “DVD Player” program, but for reasons only Apple knows, it is hidden. If you search for it, you can move it into the Applications folder, or even into the Dock for easy access. The easiest way is to use Spotlight. Click the little Spotlight icon in the upper right corner of your Mac’s screen. Search for “DVD Player, and the app’s icon will appear at the top of the Top Hits. Double click on the icon, and the app will launch.I have several external Blu-ray burners from OWC. There are other sources.
In our video lab our are Macs are frozen to OS 10.9.5. We do this because we believe OS 10.9.5 is the last version to run iMovie HD 06 with no issues. It also runs iDVD perfectly.