You're free to look for those videos using the search feature of YouTube. I did and they are real. Some of them feature thumbnails or content that are clearly disturbing or include sexual themes.

You would also believe the BBC which is linked from the article. http://www.bbc.com/news/blogs-trending-39381889

I'm going to assume you're not familiar with 4chan-like content, rather than trolling, so I'll try to summarise. Some people enjoy disturbing images/videos and are messed up enough to try injecting it in other contexts just for fun. When the previous article mentions something like "A discussion on 4Chan led users to discover a code hidden in the comments sections of some of the videos that led them to a Twitter account." what it likely means is: someone uploaded videos with extra information and then started themselves a spoof discussion that bled to other social networks via controversy seekers.

4chan-like communities are the source of things like pizzagate, raiding other networks to inject disallowed content, or doing things like posting videos of flashing colours on forums for people with epilepsy. Just getting someone reporting on it fuels creation of more videos like this.

It's not that the videos don't exist - it is a problem that kids can run into them by accident via genuine search terms. It's the coded message part, mentioning pizzagate and podesta, mkultra, etc. that's the bullshit part in the aceloewgold article. The simple explanation is that: some weirdos like to create this content and some idiots crave the controversy of making others watch it by accident.