How to Crop Video Clips in iMovie
Just as you can crop a still image in Apple iPhoto, you can improve your video in Apple iMovie by cropping to the best part of it. You can highlight an area of a scene or focus in on an otherwise distant subject, cropping out all the unnecessary elements.
Be aware that the crop applies to the entire clip.
To crop your video clip, select a clip to crop and click the Crop, Rotate, and Ken Burns button. Then click the Crop button inside the viewer. Using the handles of the green crop rectangle that appears, resize it and drag it over the crop-worthy portion of the image. If necessary, click one of the arrows to rotate the entire image in either direction.
To see what your newly cropped clip will look like, click the Preview button. If you don’t like what you see, click the Fit button to restore the clip to the full frame and try over. When you’re satisfied with the way you’ve cropped your clip, click Done.
Your cropped video might look grainy if you used a low-resolution camcorder (or shot in low resolution). Press Fit at any time to undo the cropping.