I'd say start simple, figure out what works and innovate. We've made many different versions of the videos in our tour over the last 2 years. We track what people like to watch vs. when they stop watching and try to re-edit or make new videos accordingly.
General tips I've learned:
- Keep it short. Under 2 minutes is always best
- Think about the audience.
- Don't focus on the pitch, focus on the explanation. A good explanation will do wonders for keeping people engaged.
We've also found that by using screencasting tools like screenflow, lecturnity, or camtasia we can easily and cheaply continue to create content.