Pausing mid-shot (or freeze framing) can be cheesy, but it’s a great editing technique for comic book films and over the top action sequences.
Creating a freeze frame in iMovie is easy, thanks to a clever Multi-Touch gesture.
Simply tap on the video clip you wish to freeze frame, move it using your finger so that that playhead (red line) is located over the exact point you wish to freeze, then swipe upwards over the playhead.
The clip will be broken in two, and a two-second freeze frame shot will be inserted in-between. You can shorten and lengthen the freeze frame by dragging the yellow trim handles on either side of the clip.