If the universe began to exist, this entails that something brought it into existence. Since an effect is dependent upon its cause, and in the case of the universe, the effect includes time itself, its cause must be timeless. The only candidate is God. God, unlike the universe, would not require a cause, if only because God is not held by time.
Of course, if the atheist can provide an explanation which better fits the facts, he is welcome to propose it. However, Ben did not give a reasonable answer to how the universe could begin to exist without God. Thus, he was not able to show that atheistic answers are better or have more explanatory power than theistic ones. The universe still began to exist, and God did not. At the end of the day, only one of these requires an explanation of what caused it, and I don't see that such an explanation was successfully provided by the opposing viewpoint.