The previous one I shared was using your Android smartphone. Here is a way to find the song used in a YouTube video directly from your computer using online tool.

Open your browser and enter mooma.sh into the address bar. You will get a new website now. In case you are lazy to type the text, click here.

You need to register for an account there, which will not take more than a couple of minutes. They won't allow you to track the song unless you become a registered user.

When you finish with the registration, copy the video URL and paste into the given field. You will get the name of the song used in that particular video.

If you want to download the song, use Google to search for an appropriate phrase.