[QUOTE=Cincinnati Kid;50921]
How does Fab create .iso files when vso is the burn engine and ImgBurn isn't installed?[/QUOTE]
DVDFab DOES NOT create ISO! Period!
DVDFab is removing protection, encoding, decoding, transcoding, and othjerwise tempering with the content, but NOT creating ISO. DVDFab output is folder (I.e. BDMV or VIDEO_TS) or file (i.e. .avi,.mkv, .wmv).
A "subcontractor" does ISO and burning job for DVDFab (there a three of them: VSO, Nero or ImgBurn - your choice).
In your case, when DVDFab created the content it handed it to ImgBurn to finish the job... According to you, the only flaw in this process is that ImgBurn didn't send you a telegram... well, I can offer you a hug instead.
Yes, creating an ISO is a part of "subcontractor's" job. If you open ImgBurn log file you will see it somewhere in a middle of log, in capital letters.
DVDFab offering its temp directory as a part of "paring" process.
And if you would follow my instructions, go to ImgBurn settings and make changes there instead of arguing, you would have it fixed by now.