Ask HN: How should I go about creating a product video?

I'm working on a web application and on the homepage, like many such applications, I plan to have a brief video explaining how the product works.

First, the voice-over: I think this would be better done by a professional than myself - feel free to discuss whether or not this is a good idea, but any tips on where to hire a professional for the job and the kind of price range would be very much appreciated.

Next, the video. I could make this myself using a screen-casting application, but I'd rather not. I'm looking either for a company that will make such an application for me, or a tool that I could learn that will let me create a walk-through of my product. I want cursor movement to be smooth, typing to be consistent and clicking of links to be instantaneous - that kind of thing.

Finally, how should I host it? Does anyone have any suggestions for a decent hosting platform? I'd prefer HTML5 by default which falls-back on Flash if there is no HTML5 support.

Have you ever created a product video and what advice can you give me? Thanks