I've used this add-on for about 10 years. As YouTube evolves, some of their videos can no longer be downloaded with this add-on, but it's still good to have, and they do update it from time to time. If Download Helper can't download the video I want, I use another add-on or method, such as Easy Youtube Video Downloader Express, or I use VLC media player, or any other number of methods. DownloadHelper is a good and old tool in my digital toolbox, although it certainly can not do everything, and sometimes depending on how the video is downloaded, there is a watermark.