https://chromewebstore.google.com/detail/broada-ytcomments-youtube/aebhiogbphmbblaaepehgmiabnmgoaae?hl=en
Broada YTComments - Youtube Comment Exporter - Chrome Web Store
Quickly save your Youtube Comments as CSV/Excel/JSON file with this simple one click exporting extension.
youtubecommentexporterchromeweb