OK, after much testing I can confirm the background video will extend the music playing time on the Title/Chapter page of a DVD.
After the opening menu, there is the Title/Chapter menu. This will provide the background for all titles in the finished DVD. So in my example, I would have two of these and they all must have the same background video. At first I thought this would be a real limitation because it does not always match the material in each title. But I eventually made a sort of collage of all the content on this DVD.
Here is what I found:
1) I made a 2min video (with music) and inserted this in the title/chapters page using the menu designer.
2) I made my two title DVD by selecting "create disk" and inserting my two projects.
3) I applied my new "menu" and then added music on each the Title/Chapter pages. I had to apply music because the music (sound) from my background video did not play. In this step, my music was of different lengths; 30 secs and 2min.
4) I selected "Preview" to see how it all looked. On title #1; this Title/Chapter page played the 2min background for 99Sec then repeated and simply repeated my 30sec audio 3.3 times. On title #2, this Title/Chapter page played the 2min background and my 2min music for 99sec then repeated both.
5) While the video must be the same, at least I can select different music for each Title/Chapter page!
Of note: there is much discussion on this page about using the "duration" value under the "playback options" to determine how long the menu pages will run before repeating. I had set mine to 60secs and this did not have any effect on the default of 15sec for title/chapter page but did increase the opening menu page.
Creating the background video does allow me to increase the Title/Chapter page up to 99secs.