Here's another tip for making screencasts, that i have to keep reminding myself.
If you're recording a screencast that may last more than a couple minutes, make sure to pause every once in a while between demonstrating concepts, saying and doing nothing.
That gives you an edit point if you need to cut out some material or splice in new stuff, or overdub some audio. Without the pauses you'll find no good way to edit stuff without having to jump into the middle of sentences, etc.