Camtasia is certainly among the most popular of the apps for producing training and demo videos. Mac versions of the popular Windows software first became available in 2009.
This latest version, released today, has a boatload of new features, including custom annotations, tilt and restore animations, speed tweaks, and a complete redesign of the editor interface. Camtasia has been tremendously popular for creating screencasts and many of the new features were created at the urging of users.
If you'd like to try it you can download a 30 day free trial. The software is US $99.00 for new users and an upgrade from version 1 is $49. The software requires a Mac with an Intel processor and OS X 10.6.3 or later with Quartz Extreme support.