Actually, bin Laden videos don't carry much weight in the US anymore.
To most of us he is a paper tiger. Sure, we can't wait till we get him. But his videos certainly don't make any dramatic shift in the publics opinion of Bush.
Thats not what the BBC say, Bush has always been going up and down on the polls and the reason is sometims the doubts people have but he always make sure that he comforts them by spreading more terror and fear!