Contacting K-pop stars thru Youtube?

Hai! I was wondering can you contact K-pop stars through youtube? I contacted Allyson Ashley Arm through Youtube and I received a response 2 months later. But would it be different bcuz they are international? I really want to contact B2ST. I subscribed to them two hours ago. Would it be safe? In the AAA fanmail, I put my address and it wasn't scammed or anything. btw, B2ST's youtube channel is "beastofficial". Is it really their official channel. If not, could some1 kindly tell me their real channel plz? Thanx! ~~Soneelf~~