How to Add Clips to Your iMovie Project
Review your work.
iMovie offers two Play Full screen buttons: one under the Event Library and one under the Project Library. Select the project or Event you want to play and then click the corresponding button (or press Command+G). You can also choose View→Play Full Screen to watch the selection. Press the spacebar to pause, and press Esc to return to iMovie. You can also move your mouse to display a filmstrip that you can click to skip forward or backward in the project or Event. To play a selection from the beginning, press \ (the slash that leans to the left).