Export compressed videos from quicktime screencast / screenrecording
The easy way is to export instead of save. You can go to File → Export → iPad, iPhone, iPod Touch &amp; Apple TV...

Then pick an option.

 

iPod touch &amp; iPhone 3GS is the one that give you the smaller file size with a resolution of 640×400.

For the screenshot I test it with a video of 6.9 MB.