iMovie: Crop and letterbox (ignore aspect ratio) I have a project in iMovie and I want to crop part of one of the included clips to a rectangle that isn't 16x9 or 4x3 or any standard aspect ratio. As far as I can see, iMovie will only let me crop in the shape of the current ratio.

How can I get iMovie to let me crop part of a clip to a nonstandard aspect ratio and letterbox the result?
Leaving this for future reference: now you can crop a video from the imported media section before adding it to the movie. 

iMovie will add black bars automatically to fit the video, which you can control using the cropping tool on the clip after adding it to the movie.