Gmail motion was a funny idea by Google. Basically, by moving around in random ways in front of your webcam Gmail Motion will let you control your computer screen. This is an old video and an older technology. I posted this video for two reasons.
Reason One Now you can find some info about Gmail Motion on the website.
Reason Two (The Real Reason) There is a guy in this video who acts out the different motions that you need to perform to control the computer screen. Watching him in the background is just hilarious.