As the person before me said, you can go to en.savefrom.net in a new tab, but the easier way is to just but the letters "ss" before youtube in the search bar of the video that you're in. For example, if I was on a video at

I'd make it like this instead with the double s'
https://www.ssyoutube.com/watch?v=dQw4w9WgXcQ
See how I put the double s' before youtube.com? It automatically directs you to the savefrom website