I know this is a very old post, but as for the 40mph+. that is 100% accurate. I worked with the guy who made the video for over two years, and during that period we went out in some truly insane winds, easily reaching 40+. It can be done safely (providing you are not a complete novice) in that area due to the beautifully smooth wind you get off the sea. If you still don't believe, contact the guy over youtube and i'm sure he will arange for a demo. Also they are currently being filmed for a documentry which will be on the web sometime soon. And the weekend they have been filming (27th and 28th june 08) has been absolutly manic. Not sure of the details of the documentry, again if you contact the guy who made the youtube video i'm sure he will know more.
His name is nathan and he is a kite genius, much respect to him for being a complete nut case.
ED