Even though you're not producing written content, what you put down on paper before you record will make all the difference. Let's look at outlining your audio presentation first before discussing the copywriting techniques that work as well for audio as they do for text.
This tool is a MUST USE! So quick and convenient for SIMPLE screen casting. If you're doing private stuff for a membership site...probably not the best choice. But, for simple "get the content out there" screen casts...this is a golden boy among all players. The twitter based login and integration means that sharing is an absolute snap because like you I'm sure, my twitter postings end up all over my social profiles/lifestream. Excellent!