Minitube - Minitube is a YouTube desktop application.
4K Download Online - Download music from YouTube to Android, SoundCloud to Android, Facebook to Android, Vimeo to Android, from browser to device or to desktop directly.
YouView - Browse, watch, convert, and download YouTube videos on your Mac faster, because YouView uses the core technologies of Mac OS X to play instead of Flash allowing video to run smoother on systems with lower specs.
GetGo Download Manager - GetGo Download Manager is the best free internet download manager designed for the new generation of web sites (web 2.0)
Tubbler - YouTube Movie Player for Mac OS X.
Video Downloader Professional - Video Downloader Professional (VDP) is an pretty smart and fast tool to catch videos from YouTube.