So, if it has not had the belt, rollers and sliders changed it could due for replacement, or overdue, if it was me I would whip off the transmission casing and take a look inside
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...
They are good, dare say very good, equal to the T Max, and cheaper too.
Rare as hens teeth over here.
There is a 2017 model on Bike Trader.......£5300
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!