I get that you think it's cute that whoever choreographed Seventeen's Pretty U included sign language (if indeed that's what it is) in their choreography. It is really cute. But what isn't cute is people going on about how cute it is and that they now want to learn sign language because it's been included in the video/performance/whatever.

Reasons you should want to learn sign language:

To communicate with a d/Deaf person

To communicate with a person with communication issues

Not because an artist you like uses it in a video. That's not funny or cute. It means that when it is hard or when you realise that it does actually take a LOT of work and years and years of practice and learning to become fluent and proficient, you're gonna drop it and say oh well it's too hard and I didn't really think it's that cute anyway. You're learning it for the wrong reasons, and it's not right.

Now if you think it's cute and you start learning and you think hey, I actually like this and want to help people, then more power to you. Props for finding a subject you actually want to work at and I support you for it, but you're in the minority. (the minority of a minority, I'd even go so far as to say.)

So please, don't say things like that. I don't find it funny or cute that something I and others need to be able to communicate is 'cute' because some pop stars use it, but problematic otherwise.