Screencast-O-Matic is a simple program that helps you capture screen activity on your Mac. You can work with this application whenever you wish to record a tutorial for a utility you've developed, game walkthroughs, a clip taken with your built-in webcam to share with your friends and family, etc.
The tool provides you with various video recording options (choose resolution, enable or disable audio recording, etc.), lets you preview the final clip before sharing or exporting it, and offers you several editing tools if you wish to retouch the video.
Furthermore, before saving the clip to your local directories, you can choose to hide or highlight the mouse cursor from the video and include a subtitle file if necessary.
Sadly, the application supports a small amount of output formats (MP4, FLV, and AVI). Hence, popular file formats like MOV, SWF or MPG are not supported.
The free version of this program comes with several limitations, so I'd suggest upgrading to its Pro version if the aforementioned flaw mean much to you. After you make the payment on the homepage of the developer, you will unlock options to upload the recordings to Dropbox or Google Drive accounts, share tutorials on the Vimeo website, and much more. Plus, you'll no longer have a duration limitation for the recordings (the free version allows you to record for a maximum of 15 minutes).