Great Downloader easy to use can convert into multiple file formats. Fast and impressive
MediaHuman YouTube to MP3 Converter - Extracts MP3 audio from YouTube, Vimeo, Dailymotion, Mixcloud, Bandcamp, SoundCloud and many others. Available for macOS, Windows and Ubuntu/Linux. FREE!
Video DownloadHelper - Browser extension to download videos from the Web
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
Allavsoft - Allavsoft is a professional Video and Music Downloader. It can batch download video,music files and subtitles from YouTube, Spotify, Soundcloud, Qobuz, Vimeo, Twitter, Crunchyroll, Lynda, Facebook, Dailymotion, Viki, BBC etc 1000+ websites.
Freemake Video Downloader - Freemake Video Downloader downloads videos from more than 10,000 sites. Absolutely FREE. Download YouTube in HD, MP4, MP3. **Voted best of 2018**.