That one time you need to record a video of your machine not working, or of you teaching someone how to use a piece of software or just wanting to record a video off of YouTube. Then Screen Grab is for you.
This easy to use OSX app allows you to record your whole screen or just a part for as little or as long as you like. There is also the ability to take images as well - as we all know how difficult it is to get screenshots on OSX the same size or of the same area on the screen.