I think things really took off with the people who were making "gold-digger" videos, where a guy tries to talk to a girl and she rejects him, only to come back when he walks up to a (most likely rented) exotic car. In many of these cases, all of the people involved in the video are not authentic, but there's never disclaimer that the video is staged or a skit. Even car accidents, sad stories of addiction and mental illness, and stunts can all be staged to gain views as well.
I'm skeptical of everything I see online, been that way for a long time... Worst part is there is no real way to avoid that type of content, and that phony content often gets plastered across all the sites, and reposted for years too come, and even written about when it's exposed as fake, so there's no real way to avoid it, and there's no incentive for people to stop doing it because of the (negative) popularity it breeds for the people and companies that sponsor and create it.