I have a crude way but it WILL work if you are careful enough.
First you will have to convert the DVD video to avi format. You should be able to find a lot of softwares that will do this for you. After that, use VirtualDub to take the segments you want and save them as individual avis. After that, use VirtualDub again and join them together.
Alternatively, you can use screen capture programs like Camtasia from techsmith and just simply capture the parts you want. However, personally I don't recommend that as it is possible to skip some frames on low-end rigs and you are forced to watch all the segments physically as it is recorded.