Great Downloader easy to use can convert into multiple file formats. Fast and impressive
VideoProc - VideoProc is an easy video processing software to convert 4K UHD videos, DVDs and music with full GPU acceleration; resize, cut, crop, merge, adjust, compress; download videos/music/playlists, record screen in 3 ways.
Video DownloadHelper - Browser extension to download videos from the Web
OnlyMP3.to - Convert YouTube videos to mp3 music files for free with the OnlyMP3 web app. It is the fastest YouTube to MP3 Converter to save high-quality music from YouTube.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
HandBrake - HandBrake allows users to easily convert video files into a wide variety of different formats.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.