OS X Lion: Screen Recording in QuickTime X | TMO Quick Tip | The Mac Observer: You’ll get a little black Screen Recording window from which to control your options and start recording. When you click the drop-down arrow, you’ll see even more stuff you can change, including the location where your movie will be saved.
So drag to select an area that you’d like to record, and then when you release your mouse button, you’ll be able to resize the box you’ve made by dragging the familiar handles around it. You can also click and hold on the interior of the box and drag to adjust its position on your screen.
After you’re finished making an instructional video for your technophobe uncle, click the stop button on the black Screen Recording window. QuickTime will then process your work and save the .mov file to wherever you’ve assigned it to do so. Using the “Share” menu option, you can publish your tutorial to YouTube, send it directly to an e-mail, or even put it on Facebook (if you must).