iMovie is a multipurpose application. You can use it to create original video projects, but you can also use it to store and organize your video footage and to watch video—the projects you create and your raw footage (which, in iMovie, is organized into Events). When you watch projects or Events, you can play them from the beginning or from any other point. You can also play just an individual clip in a project or Event.
To play your video:
Do any of the following:
To play an Event or project from the beginning, click any clip in a project or Event, and then click the Play button (shown below) below the Project browser or Event browser. You can also choose View > “Play from Beginning” or press the Backslash () key.
The View menu appears in a light gray bar across the top of your computer screen.
To play your project or Event from a specific point, in the Project browser or Event browser move your pointer over the frame where you want to begin, and then press the Space bar.
To play any frame range or clip, select it in the Project browser or Event browser (so that it has a yellow border around it) and then press the Slash (/) key or choose View > Play Selection.
To play any frame range or clip in a loop, select it in the Project browser or Event browser (so that it has a yellow border around it) and then choose View > Loop Selection. Press the Space bar to stop.
To play a project in full-screen playback mode from the beginning, choose View > “Play in Full-Screen Playback Mode” while the project is open in the Project browser, or press Command-G to play the project from the playhead.