If you want to rip just the movie itself (no extras, previews, etc.) it can be really tough to figure out what file the main movie's file is on some disks. Sometimes the movie producer adds a bunch of false "files" to make it real hard figure out what to copy. I ripped John Wick (BD) a couple of weeks ago; there are like 50 fake files on the disk, sometimes AnyDVD will tell you which file is the correct one - many times I just go to the AnyDVD or MKV forums to find out what file I need. Once someone figures it out, they usually post the info.
There are other options too, for example, you could rip the entire BD disk to ISO (using "AnyDVD HD" and/or "Image Burn" see
http://imgburn.com/ ) and then playback just as if you inserted the actual BD into the disk drive. But the downside to that method is that you need working menus and JRiver doesn't support menus (yet), and it takes up a lot of extra disk space. I prefer to just rip the main movie to save space and because I just want the movie - not the extra junk.
Good luck.