The Suzuki Bergman scoots (250 & 400c) sometimes make noise, it is usually described to sound like a Sea lion, that is down to worn belt and glazed clutch shoes...
Obviously I can't hear what is on the video.
Start with the simple stuff, check the brake.... also if the scoot makes the noise with the scoot not turned on and not under load you can discount the CV transmission making the sound.
Also check the oil (hopefully there will be some) in the final drive gears, they turn while the scoot is being pushed around.
Also check the wheel bearings...
These are what Dr. Pulley advise as a direct replacement for the standard rollers, they are a little lighter than the factory fitted rollers, most Dr. Pulley sliders are a little lighter, that helps with acceleration.
Add some Dr. Pulley variator sliders for better acceleration, or go the whole hog and install a J Costa variator.
Twist and go gear changing is so last century!
Just the standard Vespa engine, tuned to 45bhp by Roadspeed, nigh on impossible to put a motocross engine into a small frame Vespa, easier to just buy one of these
If that is a photo of the actual scoot I would say it looks good, it looks straight and tidy,
It would make my scoot look slow (which it kinda is) in comparison, yeh I would have one, or something else the same cc, maybe next spring.