Paste a youtube link with the format:

https://www.youtube.com/watch?v=[videoId]&lc=[commentId]

Example:

https://www.youtube.com/watch?v=iTo4Qh2R6m4&lc=Ugy1iS4N7SXfWOW1jkV4AaABAg

You can get the comment id in the link by clicking the time the comment was posted. (to the right of the username)