In DVDshrink you can customize the setting so you don't burn to the edge, but what's a good amount? thanks
I go by ScubaPete's 4360MB recommendation. I would only go down to 4300 if my backups were messing up at the end of the film. Lower quality media sometimes have problems with dye distibution at the edges, causing playback problems. If you have cheap stuff, stick closer to the 4300 mark. But if you got the good stuff, then creep on closer to the 4360 area.
I used to burn movies and fit them to 4260 with no problems. I now fit them to 4300 and the quality is still good all the way through on my Verbatim Digital Movie DVD-Rs.