I'm a little late to this thread, but wanted to post what ended up working for me. I've read everything in multiple threads, on various Forums (fora?), and kept striking out.
This is on a Windows 7 Laptop. For reasons explained below, this solution requires the 32-bit version of VLC Player.
The first part of the usual instructions given at the
frequently linked site, needs to be done. That is, download the KEYDB.cfg file, and put it in the appropriate AppData folder for your 'username':
c:\users\'username'\appdata\roaming\aacs
This aacs folder does not exist initially, so you have to manually create it, then copy the KEYDB.cfg file to it.
I also saw recommendations to put this file in:
c:\users\'username'\appdata\aacs
and so I had done this as well, but I don't know if it's necessary.
The above page talks about then putting in their libaacs.dll file (32 bit or 64 bit, depending on your VLC installation) into the VLC subfolder, but this never worked for me.
Instead, I used the dll's from the current MakeMKV program installation (see
this thread).
MakeMKV is a 32-bit program, so presumably the dll's from its installation wouldn't work in a 64-bit install of VLC (although I'm not 100% certain of this), hence the recommendation to use 32-bit VLC PLayer.
In the MakeMKV subfolder of Programs (x86), you'll find a file called libmmbd.dll. Copy this to the VLC folder, and rename it to libaacs.dll. Copy that same file from the MakeMKF folder again to the VLC folder, and this type rename it to libbdplus.dll.
Once I made these changes, I was able to successfully play BluRay Discs that wouldn't play before.
Just wanted to post this for the benefit of others who might have been pulling their hair out over this, as I was for most of the day.