Good question about the Polar monitor's moving-the-watch-to-the-strap action. I find it works about 90% of the time. It gives an audible beep when it senses that motion. Like you said, it's important a device quickly give you feedback whenr an action has been accomplished.

Yes, Apple's commercials are quite effective at showing intuitive user experiences. For example, the Mover app where you transfer pictures by flicking them to another iPhone: they only showed the app for a second, but you understood the interface right away. (http://itunes.apple.com/us/app/mover-lite/id312165666?mt=8)