I don't think there is much you can do honestly. Telling them to stop wouldn't work if they have an interest (how ever much inspired by youtube and e) they won't listen to you saying they're not doing magic right or whatever you would say to them.
You can try to do something about it but I don't think there's any hope for them to just give it up because you ask them to.
Another idea if they are interested in magic is, give them advice help them become better magicians. Explain that there is no need for ellusionist and it's wrong to expose magic (youtube). This seems like a sensible option unless all they have is a fleeting interest.
If you try to help them and they're jerks about it, just leave and try to ignore it and them.
Hope my late night ramblings have some sort of relevance.
