Y2mate is good cloud-based YouTube downloader that supports famous file formats like MP4, M4V, 3GP, WMV, FLV, MO, MP3, WEBM, etc. High speed downloads without registration. I Like the way it downloads the videos directly on the web browser by Inserting "pp" after the word "youtube" in the link to download videos and mp3 files.
4k Video Downloader - 4K Video Downloader is a software program that helps people download video files from sites such as Facebook, YouTube and Dailymotion.
SaveFrom.net - Free Online service to Download YouTube videos at one click! The best YouTube Downloader supporting fast and easy vimeo, Facebook and Dailymotion video Download and much more!
Video DownloadHelper - Browser extension to download videos from the Web
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
iTubeGo - iTubeGo YouTube Downloader for Android is an free mobile app will let you download YouTube, Facebook, Twitch, Bilibili videos on Android mobile phone. This great Android app can convert YouTube to mp3, mp4.
ClipGrab - A friendly downloader for YouTube and other sites