His father said that it was different from his experience with cysts, but we weren't given any information as to whether or not he had much experience. He is shown with an adult patient, which would lead you to wonder how much experience he would have with what is usually a pediatric condition.
Unfortunately, the video stops before we can hear what the specialist thought of it. It shows him saying that he can't explain it, but without the context, I don't know whether he was referring to some aspect of the cyst or something else. The mother indicated a midline cyst which suggests a thyroglossal duct cyst. These can drain spontaneously, as can other kinds of cysts, especially those associated with an opening, like a sinus tract.