Nousy family member, what to do?

[Anonymous]

my niece is 15, my bro is 19. He studies and has more than one hobby. One of his hobbies is to do you tube videos, you tube live streams.
Well, my brother, his wife and his 15 yr old daughter are living with me and my bro temporarily. My niece wants to know what my bro does as she "hears" him sometimes. I know what he does but it is no ones business to know unless he says so. He actually wants to keep things as private as he can, however with all them 3 living here with us, it is inevitable to "hear" him sometimes when live streaming...
my niece told me yesterday that since she is such a pro in the internet, she found one of my bros videos and she now knows what he does. This bothered me so much that I don't know what to do. If I tell her something, she will be upset. If I tell my bro or his wife, same thing. I don't know if I should tell my bro she "found him". He may not like it or he may now feel he can't be himself in you tube. Pls advice. THANKS

[apelhitam]

Once you're online, you will eventually have no privacy at all. He shouldn't be surprised. Maybe remind him to not do things he will regret

[Asker]

I see. I just find annoying that she wants to know what he is doing... is non of her business

[thomascale18]

It's only normal youtube videos right (or is it something else, not judging)? I don't think he should have to hide his hobby.

[Asker]

all normal online, he is just an American liberal guy, she is Spanish. He feels some family members may not understand him...