Screencast-O-Matic is a great site for creating screencasts for all platforms. All a user has to do is click start recording and then adjust the size of their recording window. The finished product can be downloaded, uploaded to YouTube or shared on SOM.
I highly recommend checking out Screecast-O-Matic by clicking here!!!
Below is a demo video...
For my top 10 sites/apps for screencasts click here.