He successfully gets Dawkin's to admit that he think their could be intelligent design
What he's actually done is asked Dawkins to suggest a way in which intelligent design could exist from a scientific perspective.
that he isn't absolutely sure God doesn't exist
How can he be absolutely sure that God doesn't exist, it is though, very unlikely.
nor can he put a figure on how sure he is
Because it's not quantifiable, theists always state that they are 100% sure, but you'd be foolish to believe that of all of them, but it is the nature of God bothering to be 100%, a scientist will not throw about such arbitrary figures.
Ben also makes the point that some people are happier believing in God, something tha Dawkin's tries to rebutt by rather pathetically saying he's recieved letters from people that aren't.
That's not an argument for God's existence, it is an argumentum ad populum. Dawkins merely points out that it is true on the other side as well.
Pretty successful arguments I'd say.
There is no arguments here.