This is actually quite easy. I'll use NERO as my example...
When you make a new DVD-VIDEO compilation, it puts up the default folder setup and proper ISO/UDF specs for you.
All you must do is add the video files to the VIDEO_TS folder.
But you can still add more folders and alter the UDF/ISO info as needed. Don't bother the ISO/UDF settings, as it could mess up proper playback of the DVD>
Go ahead and just ADD a new folder and put your data in the folder. I prefer to call the new folder "ROM" because it is non-video DVD-ROM material: