What does that error means? I receive that error when i try to backup 'Tomb Raider - The cradle of life' movie. It gives the error when dvdshrink checks the dvd.

When a dvd movie isn't accessible by DVDShrink my advice is to start your dvd playback software.

Check if the software can play the dvdmovie. Then try dvdshrink.

Well this is so old you may have already figured it out, but here goes - I just had the same problem, but found it because I had an iso image that would play just fine on the PC, but when burned to a disk wouldn't play on my DVD player. I got the "invalid UDF filesystem" message when trying to open the image in DVDShrink. So...I opened the image with Ultra ISO and noticed that there was no AUDIO_TS folder, just the VIDEO_TS folder. I added the audio folder, and saved the image with a new name. No more complaints from DVD Shrink, and it now plays on the home dvd player.