Removing the video and keeping only the audio?
删除视频并仅保留音频？
After you paste a YouTube URL, just select one of the audio formats available in the Download dropdown menu, and the video will only contain the audio.
粘贴 YouTube URL 后，只需在下载下拉菜单中选择一种可用的音频格式，视频将仅包含音频。