This is a new reply in response to:
http://www.dvinfo.net/forum/non-linear-editing-pc/528300-dvd-copywrite-software.html

Many people have asked how to keep customers from copy their DVD's.
One method that is suggested is pad your movie with a Black screen, and then "scratch" the outer edge of the DVD tracks that only contain your black screen
The theory is that a DVD player will faithfully play your movie from the inner track zero to the end of the movie,
but that a DVD ripper program will start copying at track zero, and then fail with a read-error when it encounters the "scratch"

So, I set-about to test the theory
1. Created a 10 minute movie, and padded it with 20 minutes of a black screen
2. Burned the movie to a clean DVD+R
3. I then took a small piece of sandpaper, and scratched the outer-tracks of the disk
4. I put the scratched disc into my DVD burner, and while I could hear the burner trying to read the disc, after about 90 seconds the Disc appeared in Windows explorer.
5. I used Imgburn to create an image of the scratched disk
6. Imgburn went about its business, until it encountered the scratches. It reported a read error, and eventually gave up with "Unrecoverable Read Error"
7. BUT, before it quit, it asked me if I still wanted to save the incomplete ISO file; I answered YES
8. I put a new blank DVD+R into the drive, and used Imgburn to burn the incomplete ISO file to the disc.
9. This disc then successfully played on both my Computer and a stand-alone DVD player.

So, it would appear that the scratching of the outer tracks is only a minor annoyance.
Additionally, If I were a paying customer, I would complain about the extra time it takes each time I try and play the movie I paid for

I've mainly stuck with making sure the program is long enough that it goes beyond the first layer on a dual layer disc. Most people won't think that they need a dual layer disc (or purchase those type of blanks) and hence it should defeat about 95% of casual copying attempts.

Andrew