It's representative of gnostic atheism, but not necessarily atheism as a whole. I'm an agnostic atheist and I don't believe there's "no god" I just don't believe there are any gods. A lot of people don't understand the difference, but it is pretty significant.
Still, I don't find it offensive. I think if Christians are allowed banners to suggest I'm going to hell, it should be okay to have banners suggesting their God isn't real. Either it's all okay or none of it is.
With this video, I think the guy lets Fox focus on the idea it's a nativity scene and a display of religious imagery and how it offends, when he should have focused more on his point that it's a government building showing exclusivity to a Christian scene in a multicultural country. And also focus on the point about atheistic banners. He said it's okay on private property or on a church, he should really have driven in that point because Fox news is a channel that likes to present atheists are a group of people who want to deny Christians their rights and to push them underground. When it reality what many of these atheist organisations is for religion to be taken out of government, to not be forced onto people and if people wish to celebrate or worship their deity, do it on their own terms and not bring everybody else into it. He could really have put emphasis on the fact it was government property and how it's perfectly fine for people to display the nativity scene, just not on government property that's paid for by tax payers, including atheists, Muslims, Sikhs, Hindus, Buddhists, Pagans, Satanists and so on.
If they had somebody like Henry Rollins instead, well I am sure it would have been a beautiful pwnage of Fox News. The man knows how to use the English language.