VOB stripping

I am having trouble with DVD backup. At the moment I am only trying to backup the movie itself and I am not interested in the menus etc. I have some successful backups with my method.This is what I am doing:

Extract entire disk using dvdecryptor.Edit the movie iso file using the instructions doom9.org (to copy movie file only). Create image from resultant files using Imgtools89. Burn image using Dvdcryptor.

The method works…sometimes. The problem is that I dont understand the significance of ‘stripping vobids’ - I have successfully backed up my ‘Triple X’ DVD - this has 12 sets of VOBs, but only one ‘vobid’ when I get to the ‘strip VOBID’ option window after having selected ‘VOB EXTRAS’. I select this VOB and it works.

However, when i try to backup ‘bridget jones’s diary’, using the same method, it has 4 sets of VOBs, but only 2 ‘vobids’ when stripping VOB IDs after selecting ‘VOB EXTRAs’. I have selected both of them, but the disc is unreadable in my standalone player.

By contrast, ‘maybe baby’ has something like 25 VOBIDs available for selection!!!

How do I know which ones to select? I have tried the ‘movie only’ option on IFOEDIT (which skips this manual selection of VOB IDs), but that always produces a bad disc or a disc that plays but only has 1/4 of the movie (ie only the first VOB files). In the DOOM9 guide, it seems to suggest that the VOB IDs should match the sets of VOB files eg if there are 4 sets of VOB files there should be 4 VOB IDs in IFOEDIT - definitely not the case.

I’ve read everything I can find, but cant find the answer to this question, and I’ve spent the last week persevering with this method, having discovered reason for previous failures was due to using Nero. Any help gratefully received!