I use Video Pad Video Editor. Maybe not the best, but the simplest-to-use I could find when I was looking around several years ago. Now, some 500 or so clips later, I'm still satisfied with it in the PC format I currently use.
Video Pad Video Editor
Clips made with this program can, for instance, be viewed here:
Sample Clips
I'm guessing those in the MAC realm are able to make and adapt clips much more readily than I can. A good example is the growing, prolific body of work produced by the guy on this forum known I think as "referee99", Greg Austin:
Be a Better Referee He might be a willing resource.
Wish you the best!