Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Shutter Encoder - Open source software without any restriction - converter all formats video|audio|image professionnals codecs and standards - swiss knife tool Windows, OSX and Linux
Video DownloadHelper - Browser extension to download videos from the Web
Wondershare UniConverter - Wondershare UniConverter (originally Wondershare Video Converter Ultimate) can convert any video to over 1000 formats at 30X faster speed without quality loss, burn DVD, compress/edit/download/record videos, transfer files to devices.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
FFmpeg - Open source multimedia suite for conversion, playback, profiling, and streaming.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.