There are typically two options available to you when it comes to downloading high definition and ultra high definition videos from YouTube. One option is to make use of dedicated desktop applications like Gihosoft TubeGet, etc. The alternative, and the subject of this post, is to make use of a free online HD YouTube video downloader site, which will allow you to download YouTube videos online without using up any additional storage space. Let's take a brief look at the 12 Best YouTube downloaders available today.