Youtube HD Downloader - Version 4.21 Youtube HD Downloader is a free all-in-one YouTube HD downloader and converter with easy and simple user interface supporting a wide range of video formats including AVI, FLV, MP4, MP3, MPG. Download Full HD, High Definition and High Quality videos from YouTube. The program is easy to use, just specify the URL for the video you want to download and click the "Download" button.