I would check out This Guide, it shows how to crop a video in Avidemux, an open source video editor. Here's how it's done,
Download the free Avidemux software from the project website over at
Sourceforge. The program is available for Windows, Linux and Mac OS X.
Install the software and load your video files via the file menu into
the application. You load the first file via File > Open, and
additional files via File > Append. You then have to replace the Copy
action under Video with another codec. I have selected MPEG-4 ASP
(Xvid) for instance.
Click on the Filters button afterwards and selected Transform > Crop
from the selection.
Click on the Configure button afterwards. This opens a preview image
of the video. Enter pixels in the left, right, top or bottom fields to
crop the video. The values are immediately shown on the preview image
so that it is easy to fine tune them. You can also try the auto crop
button which picked up the black bars in my test video nicely.
Click on the OK button to accept the changes. You can then click on
Preview in the previous configuration screen to see how the cropped
video will look like. If you are satisfied close the window.
All you need to do know is to save the video via File > Save > Save
Video or with the Ctrl-S shortcut. The process may take some time
depending on the performance of your computer and the length of the
And that's all there is to it. This is without doubt one of the
easiest way to crop a video.