You can automate screenshots in mac os x with screenbar. It’s a menu bar application from where you can start and stop a timer that takes a screenshot on a set interval of seconds.
A newer version with updated GUI and functions can be found on Mac app store
I’ve written before about a terminal script that takes a screenshot every 5 seconds and saves it to your desktop. That is what Screenbar does but you get a user interface in the menu bar where you can start and stop. You can also set how many seconds the program should wait before taking the next one. I needed this program myself when taking screenshots for a game i’m working on.
To start taking a series of screenshots you click on the Screenbar icon and select Automatic Screenshot. They will we saved on your Desktop.
To stop the automatic screenshots go back to Screenbar and click Stop automatic screenshot.