iMovie '11: viewer
The iMovie viewer, which occupies the area in the upper-right corner of the iMovie window, is where you view your project or Event video when you skim or play it. It displays whatever is beneath your pointer at any given moment.
You can resize the viewer by doing either of the following:
To resize the viewer, do either of the following:
Choose Window > Viewer > [size].
The Window menu appears in a light gray bar across the top of your computer screen.
Drag the light gray horizontal toolbar in the middle of the iMovie window up or down.