YouDown

YouDown is a simple, free Windows application that allows you to download HD videos from YouTube. The process is simple: just enter the URL of the video(s) that you want to download, select the desired quality of the video, and choose which folder to save the result to. You have three choices for video quality: normal, high, and high definition. Videos are saved in MP4 format. There you have it: YouDown, another program to keep in mind when you want to download high-definition YouTube videos.