06 Jun 11, 04:50AM
My screen's size is 1280 x 800, I got a Mac as well, and same thing happens to me when I record fullscreen. In the AC launcher simply select windowed and choose a screen size that fits most of the screen, for me it's 1152 x 720. I don't know if Quicktime Pro lets you crop the video to a smaller size (I use Screenflow and Screenium) so if not, I'm pretty sure that you can crop videos/images in iMovie anyways.
HTH.
HTH.