myrdd
commented
5 years ago +1 for comments. see e.g. https://github.com/egbertbouman/youtube-comment-downloader, which provides the comments as json or csv
I'd love to have the playlists stored as well. that is, which video is in which playlist—maybe even in multiple.
Save (and keep updated) more than just the video title. youtube-dl can also grab a video's description.
Maybe add optional version control (git) support to keep track of changes to metadata.