Downie - Video download for OS X. Downie supports at this moment over 1,000 different 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.
Video DownloadHelper - Browser extension to download videos from the Web
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
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.
ClipGrab - A friendly downloader for YouTube and other sites