Hi Paul,
Like Eric said the prev/next buttons should move you around between chapters on a single track. Do you have your videos on separate tracks? If so, you might try putting them all on one track and using stories to create the functionality you describe.
Here's a link that describes the process:
http://www.kenstone.net/fcp_homepage/dvdsp_playall_russell.html
You will need to put all of your videos on the same track and create chapter markers at each new video. From these you will create separate stories. Your buttons will then be pointed at stories, and each story can have its own end jump.
I can't say for sure, but I believe the prev/next buttons would then jump to the next chap. marker on the track. However, on the first and last markers you should disable the prev/next buttons in UOPs. Software DVD players are notorious for skipping to erratic places. This procedure is documented in the DVD Studio Pro manual Chapter 17, p. 602. If you don't have a hard copy manual, try searching for "getting consistent previous and next button behavior."
Good luck,
Brent
Associate Professor
Illinois State University