You should not take it so seriously. It is meant to capture your attention and apparently it did.
As I understand it, the Americans names that element first but didn't follow the "rules" that were used for previous naming/pronunciation, and so the Brits corrected it for them. But were they grateful ?
Actually, it was a Brit, Sir Humphry Davy, who first called it Alumium, then Aluminum. The name was changed to Aluminium to conform to international standards. And, as we all know, the Yanks are not very good at conforming to international agreements.
Only found this post when I decided to google the ad because when the UK guy 'incorrectly corrects' the US guy it drives me mad too! If it's clever advertising, it's a bit too clever for its own good imho, because hardly anyone I know has noticed it! (Eccles - we are obviously too brilliant for our own good too!)
On the periodic table it has been agreed Internationally to be spelled Aluminium, so.... the UK English pronunciation is correct. Unfortunately the advert should say 'it has an 'i', not a 'u'. The U.S. pioneers were mainly illiterate or came from non-English speaking countries, therefore spelling mistakes and poor grammar have become accepted over the years and called American English :-)