I'll correct a few misconceptions in this thread, so that someone else who might read it in the future isn't led astray.
My DVD and BD folders are in External HD. No any rip, they are full DVD and BD( with menus also!)
These are rips. You have copied the contents of the discs to a Hard Drive. That is called ripping, and the result is a rip. Whether it is a full rip with all the menus, or a title-only rip with just the movie, it is still a rip. The term rip does not necessarily mean the copy is further compressed or degraded.
In other words, I would like to know if, once the contents are imported in the library, I can run the individual tracks as is the case with audio CDs.
DVDs and BluRays don't have "tracks" in the way that you understand them from CDs, where each song is atomic and self-contained in an individual file.
Video discs have Titles. A Title is a logical grouping of one or more files that together constitute a complete piece of content. On a movie DVD or BluRay, a Title would be the complete movie. A title can be composed of many files, if you do the rip the way Mozartino has. A single title might have 50 or more files of different lengths. It's an inconvenient artifact of the mastering process.
Titles have Chapters. A chapter is nothing more than a metadata based marker, that gives a time range within the Title. A concert video would commonly have the performances of different songs marked as Chapters. Chapters are NOT necessarily separate files.
If I recall correctly you cannot rip BD disks into the library - as all Blueray disks require a hardware chip to decode the media them which is present on the BD Player - this is a licensing issue. ... Some of the other experts here may chime in to confirm or contradict me 
This is not correct. MC cannot rip (or add to the library or play) encrypted content. It can handle unencrypted content. You can add BD rips to the library just like DVD rips, as long as they have been decrypted.
There are many tools that do this. Some, like DVDfab, decrypt on the fly while the disc is in the drive. Others decrypt during the rip. MakeMKV can also do this.
is it possible to have 2 libraries on JRiver, that is, one for audio CDs and the other for music videos? I ask this because by not being able to tag and import the file into my library, I can accept the solution of 2 libraries. Thanks
It is possible to have two libraries. Read this article:
https://wiki.jriver.com/index.php/LibraryIt is however not desirable to have two libraries, nor is it necessary. It is possible to import and tag the files.
In my opinion the best thing to use is MakeMKV. Newer versions are capable of decrypting on the fly for MC if that option is selected. MakeMKV can create full backups of BluRays including menus, or it can do perfect title-only rips where the content is losslessly ripped into a single file (without menus). If you create a full backup using MakeMKV, you could then use a separate utility to make it into an ISO image so that MC can have it in the library as a single complete disc.
If you want to treat the chapters in your content as separate "virtual tracks" so that you can see and play them individually from the MC interface, MC has a feature for this: Particles. Learn how to use Particles here:
https://wiki.jriver.com/index.php/ParticlesIf your content does not have chapter markers, you will have to create them if you want to use Chapterfy (chapter markers are not required to create particles manually). MKVtoolnix, which is a companion utility for MakeMKV, has a chapter editor that can create and edit chapters in an MKV file.
Jmone wrote a utility called Chapterfy that automates the process of creating Particles from movie rips. Learn about it here:
https://yabb.jriver.com/interact/index.php?topic=100436.0I don't use it, so I don't know if it works with full or ISO backups that include the menus. I don't know if it will read the chapter markers encoded in an MKV, as the docs only seem to refer to grabbing a separate chapter file from ChapterDB. If it doesn't work with built-in MKV chapters, it should. Perhaps Jmone will stop by here and tell you more about it.
If you want to have individual songs in an opera or music video be individually viewable and playable as tracks in MC, my advice would be to forget about the menus, rip the title as a single-file MKV using MakeMKV, make sure your chapters are as you want them, and then create particles for each chapter (hopefully using Chapterfy).
Carry on....
