Chochise49, I have used a free audio ripper in the past. This program would rip the sound track from any DVD, commercial or non-commercial. What you got after this ripping was MP3 music clips that were as long as you wanted. In other words, if you wanted all of your MP3 clips to be 2 minutes, you just told the program to make all of the ripped MP3s be 2 minutes long. Then, in your video editor, you could break each MP3 down further to get just the part you wanted. Over the past 10-12 years, I shot a lot of digital video of my grandsons skiing. They loved for me to edit these videos, add some wild music, do slow motions of their jumps and skiing through terrain parks with rails and such.If you start out with some good raw video, you can do wonders with a video editor. You can cut out all of the bad stuff, change speed, add your own music ripped from a commercial DVD and a whole lot more.
The biggest problem with 8mm, no sound and a very inferior picture quality. I don't say this to knock your 8mm. I think this of mine.
I agree with '1775', let Costco put it own on DVD. They do a good job of getting it into a digital format. I'm not familiar with software to rip Costco's DVD but I don't doubt that there might be a program out there that will do that. After you rip this DVD, I think you will likely have the raw material to put into a video editor. If that is the case, you could then cut and snip and keep just what you want. You could then add your own music to different scenes, add titles, transitions, and more. But, in the end, it will still be 8mm. It will still look like the original 8mm.
For me, I am going to just live with the Costco DVD's. It is a lot better than having just the old 8mm. I can watch them any time I want to and don't have to keep an old projector to see them.