I'm using a mac now. The YouTube converter on my mac is Cisdem Video Converter for Mac.
You can find the video on YouTube, add its URL to this app, then start the download.
Try this one converter https://benstoolset.com/video-converter
haha, it's hard to find a virus free youtube downloader these days.. Check out maybe http://youtubemp4.site/ will work for you, it's fresh, so it has no ads or popups, which usually bring those nasty virii...
I personally use this Youtube converter and Youtube to mp3 converter its works great.