Use QuickTime to combine many clips into one
Lots of great tips in this post; read the whole thing. But I really like number 9: "You can use QuickTime to combine video clips into one. QuickTime is far simpler than iMovie."
- Step 1: open a movie in QuickTime and place your movie "playhead" cursor at the end of the clip.
- Step 2: Drag & drop the 2nd movie to the open window. Then repeat to add more movie clips.
- Step 3: Export, or click the "Close" button and save the movie as a single file.