Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Video DownloadHelper - Browser extension to download videos from the Web
VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
Knowthelist - Knowthelist - the awesome party music player Easy to use for all party guests
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
MixTape - Home of MixTape, an OSX application for creating beat matched mixes with simple export to the web or iTunes.