YouTube Comment Scraper is a free application by developer Philipp Klostermann.
The application allows extraction of comment tracks for YouTube videos using YouTube’s API. The data is stored in data sheets with the comments and additional information, and can be downloaded in .json or .csv formats.
An easy to use online service has been offered but is presently not working. Since the online service remains online and a solution is expected, it is included below.
In the meantime, it is possible to use the application locally with the command line software presented in NetLab’s tutorial which you will find at http://www.netlab.dk/services/tools-and-tutorials/youtube-comment-scraper/.
Important: The YouTube Comment Scraper online service is presently not working, but the website remains, with a message that the developer is working on a solution. The online service may be found here: http://ytcomments.klostermann.ca/