There are many ways and programs to use to download Youtube videos to your computer. I use to use and recommend Ummy but it went from a Free to a Full paid model. I used YTD downloader. It's ad supported. I don't mind if it's not to annoying, then it got to annoying. I then had an extension called SaveFrom.net but Opera recently warned it it had become malicious.
So now I' trying the 4K Video Downloader - www.4kdownload.com/.
At the time of this writing it doesn't come with any bundled with any third party software to worry about. It's pretty simple to use. It's been my experience that most of these programs work the same way. First I like to go into the Preferences and change a couple things but in this case the options I was looking for are not there.
So I clicked on the Smart Mode button, looks like a light bulb, and sure enough, the options where there to change quality or resolution and to change the download folder. I at first though they where options you might have to pay to enable because they where unchangeable but then I checked the Enable Smart Mode I was able then to access the options listed below it.
Just click on one of the options listed to change it. I left the Format on MP4 - Video.
In Quality I usually use 720p. My Acer desktop cannot play back any higher than that.
You can choose the Subtitle language if you want.
And in my case I have two hard drives and I have a download folder set up so there is where I want my videos to go. So I used the Browse button to switch to that folder in question.
So now we are ready. Open Youtube find your video. Click on the Share button under the video.
In the box that opens click on copy. Then go to the 4K Downloader and click on Paste link, big green button, and that's it. Your video should start downloading.
If you require more help using this program try these tutorials on their site https://www.4kdownload.com/help#howto
Enjoy your videos.