It's a battery operated flying saucer tin toy.
It comes with foam plastic balls which it can balance on the jet of air.
I wanted one for my daughter. Found one on eBay many years ago.
Unfortunately, the jet of air isn't powerful enough to float a real malteser.
I think for the advert, they either faked the maltesers with the real foam balls, (easiest solution) or they had a customise toy with a powerful blower.
I briefly considered hacking the toy to add in a faster motor etc but thought better of it!