I ......I am ashamed to say that I am a smoker. But I personally will never smoke on camera. It is not something that I like to broadcast or let people know about. Many people are surprised when they find out I smoke. In regards to Youtubers smoking...I think it's their choice. But if you're a big Youtuber with a large following, many of them being young and impressionable, I would hope that they wouldn't. I would never encourage smoking as I absolutely hate it :/
Damn, it didn't work out then?
I'm a non-smoker butI don't see the issue from a morals point of view which I think is the question here. Like the others said, it's the person's right if they want to smoke or not on camera. Having said that, if it was a Vlog talking to the camera kind of video, then I would probably find it a bit annoying / distracting seeing (and hearing) the person stopping every few seconds to take a drag on the cigarette. In the same way, it would be mildly annoying if they were slurping on a cup of coffee or something lol. But other than that, from a health / morals point of view, it wouldn't bother me at all.
If the issue is that parents are concerned that young children are going to be influenced by it, then maybe they shouldn't be on the internet in the first place.