Hey,
Just wanted to share a problem I had and the solution. Didn't find any thread talking about it so I thought I'd share with you the problem and solution.
I was getting an error "Posix Error - Permission denied" on both Blu-Ray I tried to rip.
The problem was (I think) related to trying to save the data on an external hard drive that was formatted in Mac OS Extended (Journaled) Encrypted. Formatted it in Mac OS Extended (Journaled) (not encrypted) and the copy started without any problem.
It might also have been that I didn't have the permission to read/write the drive because it was a Time Machine backup hard drive. For some reason, the permissions were changed as soon as Time Machine labeled it as a Time Machine hard drive.
Hope it can help someone else!