Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Video DownloadHelper - Browser extension to download videos from the Web
TwistedWave - TwistedWave is one of the unique audio editors that allow you to edit your music file online without any installation.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
Radium - Radium is a music editor with a new type of interface.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.