From Optflux
If you’d rather do without the problem of downloading a specific download online videos to download your selected YouTube video, you could use an online tool. Though there are lots of web-based download platforms for YouTube, GetanyVideo is our current favorite. It’s clean and fast and won’t perhaps you have clicking through pages which spawn popups or any other intrusive ads.
1: Get the YouTube video you would like to download and duplicate its URL through the address bar at the top of your browser window.
Step 2: Navigate to the GetanyVideo home page.
Step 3: Paste it into the bar that reads “Enter the video's link...”
Step 4: Select your selected video format and click on the respective blue “Download” button for the right-hand side.