NetVideoHunter is my favorite tool for downloading youtube and many other forms of videos. It's a Firefox add-on that puts an icon on your browser. Every time you start a youtube clip, the clip is added to a list that opens in a small window when you click the icon. From there you can save it anywhere on your computer you want, or designate a folder as the default destination. I've used this for years. Don't know if it's an option for other browsers. Check out https://addons.mozilla.org/en-US/firefox/user/netvideohunter/?src=api
9xbuddy : Simply The Best Online Downloader! is better than anything in this thread so far by far.