This video explains and shows how to join related clips in iMovie 10.

This tutorial works from iMovie 10.0 to 10.0.x (10.0.3 latest version)

Partial Transcript: Has this situation ever happened to you where you just….. Even though its part of the same clip, well there’s a way to make this easier by merging the clips together. This option isn’t that obvious but you have to go to Modify…