First, his treatment of the Kalam Cosmological argument,
And second, his treatment of the moral argument,
What makes these arguments so effective is they both start with premises that pretty much everyone agrees upon. For example, science has established the beginning of the universe and everyone lives as if morality is objective (even if some claim to not believe it). The arguments then proceed to show how these commonly accepted facts lead inexorably to belief in God.
Are these videos exhaustive treatments of these arguments? Do they address every possible objection? Of course not. They aren't meant to. Rather they are meant to quickly show how belief in God is rational. I wouldn't necessarily expect a hardened atheist to immediately convert upon seeing them, but they are good grounds for starting a conversation or for introducing these types of arguments to those, both theists and atheists, who might not be familiar with them.
Either way, they are worth a watch. Enjoy!