GitHub - shaked6540/YoutubePlaylistDownloader: A tool to download whole playlists, channels or single videos from youtube and also optionally convert them to almost any format you would like
YouTube Video and Audio Downloader extension - Opera add-ons
GitHub - soykothasan/YouTube-Downloader: This script will allow users of your site and you can easily download any video from YouTube. It is possible to download video of different quality (from mp4 to