Steve uses PLEX to stream his home media. He's got over 400 movies on his hard drive. But his DVDs have VOB files on them. How does he rip them so he can add them to his PLEX system? Leo says that what you want on your hard drive is the movie itself. Not necessarily the VOB file. But PLEX should be able to read it. A far easier thing to do is to use Handbrake to convert your DVD movies to MP4 files. You may also need VLC Media Client. They both work together to rip your DVD and save the movie as an MP4 file. Then save them to your PLEX hard drive.
Another option is MakeMKV. That will take all the files on your DVD and transcode them into a single file.