Depending upon which program you surf the net with, look at the addons available for that piece of software. See if a Youtube download addon is available for your web browser.
I use Firefox, and it does have a Youtube download addon available, every video I watch on Youtube has a download button below the video.
If you do download a Youtube video, make sure you follow the current laws for using other folks content – https://www.videomaker.com/search/google/using%20other%20people%20content?query=using%20other%20people%20content&cx=016301996033947342722%3A-xsmlwign8w&cof=FORID%3A11&sitesearch=
