I'm using DVD Decrypter and AnyDVD to copy movies, using my Plextor PX716SA. This setup usually works fine, but I've been copying some movies loaned to me that are quite scuffed up, and have only started watching them.
When I watch them, the video will halt, then continue after a jump - the audio has no problems. Also, I see large green blocks pop up every so often, and sometimes regions of the screen pixellate.
Are these things likely to be caused by bad copies, or by the scratches on the disk? I don't have the originals anymore, so I can't go back and check if they have the same problems. Also, the DVD ripper might not translate errors it reads on the discs (from the scratches) as well as my player does, so it could be the process itself introduces these effects.
Anyway, is there a generally suspected cause for these particular artefacts?