Screencast-o-matic has too many limitation. Instead, try My Screen Recorder. My Screen Recorder is one of the best screen recording software. It records your screen and audio from the speakers or your voice from the microphone – or both simultaneously. The recordings are clear and look great when played back on your website, uploaded to YouTube or used in your presentation. One thing often overlooked – It will record directly to standard compressed format that works with any video editor or any tool, no conversion required. And, the file sizes are small, making them easy to upload or distribute.
http://www.deskshare.com/screen-recorder.aspx