This site is most popular among the youth as they get opportunities to learn a lot. Videos related to every field is available here. I have learnt a lot from here.
Not only learning, you can also create your own channel and earn from there by uploading videos that are useful for the people. Youtube pays for every 1000 views.
It is easy to download videos from there in case if you want them to see the videos again and again then you can use the option watch later also.
Apart from all this you can also share videos with your friends which you think can help them in growing. It is a boost or a bane that totally depends on your perspective.