Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
Downie - Video download for OS X. Downie supports at this moment over 1,000 different sites.
Video DownloadHelper - Browser extension to download videos from the Web
ClipGrab - A friendly downloader for YouTube and other sites
4k Video Downloader - 4K Video Downloader is a software program that helps people download video files from sites such as Facebook, YouTube and Dailymotion.
JDownloader - JDownloader is a free downloading tool that enables you to download files from over a hundred hosting sites. The tool is compatible with Linux, Mac and Windows operating systems. Read more about JDownloader.