Is there any Mac software to help me crop video size?
It seems that you can do this directly in iMovie:
Miro is free and also good to "convert" videos to smaller size. Have also used Video Converter - Clone2Go at some points to make a better file to youtube. Think it was free at some time in MAS
At the end of the day it depends on your source file.
iMovie can crop videos and comes with every Mac but it only supports selected formats.
MPEG Streamclip has a crop option when you export the video.
Follow the instructions in the link below which uses Quicktime -
From my experience the one-in-all solution for Mac video-editing tools is Jahshaka</a. In comparison, it works as great as Adobe Premiere Pro, and best of all - its free! You can edit audio as well, and version 3.0 should be put pretty soon, I guess.
sorry for the wrong html.
How to Crop Video Clips in iMovie