Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Video DownloadHelper - Browser extension to download videos from the Web
Aiseesoft Video Converter Ultimate - Aiseesoft Video Converter Ultimate is professional and powerful video software to enhance video, convert videos/DVDs and videos
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
HandBrake - HandBrake allows users to easily convert video files into a wide variety of different formats.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
Vidmore Video Enhancer - Vidmore Video Enhancer provides one-stop solutions for you to enhance video quality, upscale resolution from SD to HD, optimize brightness and contrast, remove noise, reduce shaking and more on your Windows & Mac.