Gruber's right; this demo video for the new iPhone Twitter-posting app Birdhouse is a model of its class, and is required viewing for everyone who might ever need to make a demo video of anything. Even if they hate Twitter.
Click to view
(Yes, I am likely to drop the $4 on this, since
I have been Twittering a lot lately, and feeling like I'm just starting to get the hang of making tweets more clever than the mm-bacon-time-to-wash-my-socks category. Something like this might be useful.)