It's not a well-known feature, but you can actually use VLC (http://www.videolan.org) for screencasting.
Go to Media > Open Capture Device > Capture Device, and select Desktop. This will open your desktop as a video source.
Then you can either use VLC's streaming feature (Media > Streaming) or record the desktop to a file by enabling recording controls (View > Advanced Controls).
I did a DVD training series for PHPTR and we used Snapz Pro X. Works really well, and supports a lot of crap that perfeshunnal video people seem to understand (I just did what I was told).
Go to Media > Open Capture Device > Capture Device, and select Desktop. This will open your desktop as a video source.
Then you can either use VLC's streaming feature (Media > Streaming) or record the desktop to a file by enabling recording controls (View > Advanced Controls).