It is an advert about nothing. This clip made its debut on US television last night, bewildering viewers by showing Jerry Seinfeld and Mr Gates trying on shoes in a discount shoe shop. Then buying some shoes. Then leaving.

But it’s not an advert for shoes. Neither man has fallen that far since quitting the things that made them rich and famous. See if you can guess what it’s for.

Of course you know what it’s about and for – Windows. Microsoft’s bunging $300m into a new marketing campaign, designed…