This is a stand-alone utility which gives you the possibility to watch videos on your computer from the hard disk or from YouTube. You can't download the videos playing, because FDM doesn't have this feature implemented. I advise you to browse the YouTube video with your browser and then you can use the FDM application to save the videos to your computer. If you still encounter problems, access Google Search and look for an online service. This way you will eliminate the need to use an application to save the videos.