Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Video DownloadHelper - Browser extension to download videos from the Web
Downie - Video download for OS X. Downie supports at this moment over 1,000 different sites.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
Save IGTV - IGTV Downloader - Save IGTV Videos on any device with the fastest IGtv video downloader.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
Softorino YouTube Converter - Download YouTube video & audio. Watch and listen offline