I hadn't watched the video.
It's just a weird response. She's asking about the Metal scene in Japan with artists like Crossfaith and Babymetal, the next part of her question is difficult to understand but I assume she means that they are getting recognition outside of Japan, and then he goes out of his way to say they're not a band... Technically he's right, they're an idol unit. But I don't think that was the point of the question.