Kev,
Sorry to say, but it sounds like almost every 2 stroke I've ever heard. Videos always seem to distort the sound, maybe the mic in the camera, but I think what you're talking about is that rattly sound along with the exhaust/intake noise. The primary gears which always rotate are not the precision cut that we'd all like to see so they do produce some weird noises. A small dab of grease on them will help but for the most part the clutch noise is normal. Some guys have had luck with gluing a sheet of foam rubber to the outside surface of the clutch cover; I made a thick rubber gasket from 'O' ring material which helped cut down on the echo through the aluminum cover. My advice? Get on that good looking bike, ride it and try to ignore the built-in noise that is inherent to these little engines. Sweet looking ride, by the way. How's it run?
Tom