Youtube is the world’s largest and most famous video streaming site. If you have any doubts, just check its Alexa ranking. It is free and has lots and lots of videos, probably more than what you can think of.
On the other hand we have hulu plus, a paid streaming site that is available to US people only. And guess what lots of people have actually subscribed to hulu plus. This is because they specialize in uploading currently telecasted TV shows within a few days.
So if you are living in United States and love TV shows, hulu plus is best for you. Else go for youtube.