Do you have Mozilla Firefox? If you do, go here and install this add-on. then go right to the You-tube page the video is on, and click the icon, right click the button it gives you, and save-as. Save as a .flv file. then you'll need to find a flash player. This is the best way I know of without buying anything. If you want I can e-mail you a good Flash player and converter...
https://addons.mozilla.org/en-US/firefox/addon/2390