OpenShot Video Editor: Separating Audio & trimming; and also Celestia, which shows planet locations.

Say you want to put sounds from one clip on another: here's the basics of how to go about that. And showing another program found on SourceForge, that's really cool too. Remember to save the project before exporting the video, otherwise it may not exist and any work is lost once closed. -_- OpenShot seems a versatile program which is easy to use, so try it out and figure out more than I have so far.