GTK YouTube Viewer - A lightweight application for searching and streaming videos from YouTube.
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.
FreeTube - FreeTube is an open source desktop YouTube player built with privacy in mind.
ImTOO Download YouTube Video - ImTOO Download YouTube Video is a free YouTube video downloader software!
Minitube - Minitube is a YouTube desktop application.
Video Downloader Professional - Video Downloader Professional (VDP) is an pretty smart and fast tool to catch videos from YouTube.