RecordMyDesktop is a program for recording screencasts. I was trying it out today when I encountered some unexpected results. I started recording, but couldn't find a way to stop. The program was in the Gnome 3 notification area at the bottom of the screen, but clicking it resulted only in the top Gnome panel disappearing. Fortunately I found a solution on Google before my HD filled up. There seems to be an incompatibility issue, which can be avoided by unticking a couple of (non-essential) options as described in the link.
Here's the screencast of the unstable behaviour. All-in-all a success, despite the hitch. A screencast review of Gnome 3 is a upcoming project.