Dual Layer DVD's introduce more things that can go wrong. Never use it unless you have something longer than 2 hours.
"One-off" DVD burns, the ones we do in our computers and other consumer DVD burners, are never 100% compatible with everything. The plastic is soft and very fallible so that low heat lasers can etch into it.
When you send a DVD to be "replicated" or you buy a Hollywood production (which is also "replicated), it is made from a "glass master". They take the "data" (not an actual DVD) and form it into a mold, into which very hard, non-burnable, super durable plastic compounds are injected in to.
Thus, when we create one-off burns ourselves compatibility becomes a major, unavoidable issue. There will be some DVD player somewhere that just won't like your one-off burn. Software DVD players in computers are the absolute worst offenders, too. It has nothing to do with the application creating and burning the DVD, don't let anyone fool you about that. I'll give you some guidelines.
Here's some things to try:
- Burn at slow speeds, not high speeds. Fast burns like 8x and higher are more prone to mistakes. DVD players have error correction built in, but there can be burn glitches they can't decipher.
- Use known quality brand blank DVD media. Be sure you're using something like Taiyo Yuden or RiTek. I've never had issues with those two brands. Stay away from Maxell, Verbatium is debatable. You can find good deals at www.supermediastore.com
- Compress your MPEG-3 video file and AC3 audio file with Compressor. You are able to control data rates and such there. If you want to compress your own and get the best quality possible, there are two great resources. The first is www.thedigitalguy.com run by Bruce Nazarian, who is a good friend and the most knowlegable person about optical media in the world. Also a book called "Apple Pro Training Series: Compressor 3.5". That book is valid for the current Compressor 4 and has everything you need to know about Compressor in it.