Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Video DownloadHelper - Browser extension to download videos from the Web
MKVToolnix - MKVToolnix is a set of tools to create, alter and inspect Matroska files under Linux, other Unices...
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
MKVCleaver - MKVcleaver is a GUI (Graphical User Interface) for mkvtoolnix, designed to extract data from MKV...
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
HandBrake - HandBrake allows users to easily convert video files into a wide variety of different formats.