I have used one that is named "Free YouTube Downloader" by Viddly in the past but for me one version would work and the next one would lock up when I put in a url. Then the next version would work for a while. Those problems could be because I am on Win
7 or it could be Youtube making proactive changes to intentionally break it, I do not know. When it works it works
great. That is a resident app and not an online service.