I was reading this article
and near the bottom of the page they start talking about booktype. I don’t understand what this is. Are they changning some setting on the dual layer dvd so that its compatible with dvd players or what?

You will find the answer to your question here. Just search for Booktype and Bitsetting and you’ll find lots of threads that already deal with this topic.

[](Compatibility Bitsettings / Book Type Field)