Does Baptism Wash Away Our Sins Response

In this episode, Dr. Betters answers the question, "Dr. Betters, I don't totally disagree with your answer to “Does Baptism wash away our sins?” but what about passages like Acts 2: 38. As well as others. or the Ethiopian eunuch who was baptized on the road by Stephen. I'm confused because it clearly says that they must be baptized. Thank you"