Question

How to add reply to youtube’s video comment using API with PHP?

Answer 1

This library seems to make it pretty easy to add a reply comment: https://github.com/jimdoescode/Zendless-PHP-YouTube-API

/**
 * Add a comment to a video or a reply to another comment.
 * To reply to a comment you must specify the commentId
 * otherwise it is just a regular comment.
 *
 * @param string $videoId the video the comment goes with.
 * @param string $comment the comment
 * @param string (optional) $commentId the id of the comment to reply to.
 * @return mixed false if not authenticated otherwise the http response is returned.
 **/

 public function addComment($videoId, $comment, $commentId = false)