Traditionally the US Super-bowl is a place where many new advertising ideas are tried, and some go on to change the way the TV and video advertising markets work – that’s quite possible with the way that Fox is experimenting with its sports coverage advertising. Usually Superbowl advertising is the domain of the very rich and powerful, and no small business would look at trying it – it’s too rich for their blood to risk an entire campaign which might be missed in the blink of an eye. But Fox plans to offer the event in a few weeks, streamed for no charge and instead pay for it out of adverts sold for it by its affiliate local broadcasters, of…