
Add an instant replay effect in iMovie on Mac
You can add an instant replay effect to a clip, so the clip plays again at the speed you choose. You can also make a clip appear to rewind.
Add an instant replay effect
- In the iMovie app  on your Mac, select a clip in the timeline that you want to add an instant replay effect to. on your Mac, select a clip in the timeline that you want to add an instant replay effect to.
- Choose Modify > Instant Replay, and choose a speed from the submenu. - The clip lengthens in the timeline, and two speed sliders appear at the top. You can adjust the speed of each section by dragging its slider. - An “Instant Replay” title also appears over the instant replay section of the clip. To change the title text, see Modify titles in iMovie on Mac.  - When you play back the clip, it plays forward normally, and then plays again at the speed you chose. 
Add a rewind effect
- In the iMovie app  on your Mac, select a clip in the timeline that you want to rewind. on your Mac, select a clip in the timeline that you want to rewind.
- Choose Modify > Rewind, and choose a rewind speed from the submenu. - The clip lengthens in the timeline, and three speed sliders appear at the top. You can adjust the playback speed of each section by dragging its speed slider.  - When you play back the clip, it plays forward, reverses at the speed you chose, and then plays forward again.