To: DaveH
This can easily happen due to some features available in the program. First of all, after building a project in AVS DVD Authoring the appropriate DVD structure is created. In HQ it can demand more than 7 Gig in size. In addition, the program lets you add menu and chapters, as well as background music to your movie. However please note that there are project build settings offered in the program which can be used in order to adjust output file size. So you can choose between HQ, GQ, SP and LP quality. The better is the quality, the larger is the output file size.
Hope my explanation is sufficient