Will I waste data if I watch Youtube videos? How much does it use?

@SW-User Right now, I have 10GB of data.
I want to watch videos because it helps me sleep. I can't sleep without it.
I don't have Hulu, but my brother likes it a lot.

@SW-User No, my dad turned it off. :(
Yes, I can check. But I'm afraid I will use it all as well because my dad would yell at me.