Comment Originally I didn't know, but I'll answer. The quality is really good. It's easy to understand the flow of security to some extent, and it's really nice to see you lecture while keeping to the architecture. But please buy a good and expensive microphone.. The enter sound and the voice are small, so sometimes I can't hear the voice, and the sound of pressing enter! is often louder than the voice..ㅎ Anyway, the quality is really great. Thank you for uploading the lecture.