I didn't catch every single one of these (in fact, I hadn't even seen all of these until now), but the ones that I did see I can proudly say that I accurately called them out for being fake. It turns out that a good number of high-profile viral videos from the last 2 years on YouTube were indeed faked by an Australian company called The Woolshed Co.
The total of 8 videos from The Woolshed Co. garnered approximately 205 million views and a ton of virtually free press on television and online.
Part of my skepticism of these type of sensational viral videos comes from the fact that they are almost always too perfect. If you look at true viral videos (for example, the two recent tragic videos of the shooting of 2 separate black men), they are almost always not showing the actual incident. You might hear it off camera because the person filming is truly filming an unbelievable event. I would imagine that shock would take over and unless you're a trained cameraman (and most people aren't) you won't necessarily be pointing the camera right at the action.
Earlier this year, Captain Disillusion posted a video debunking a bunch of these sort of viral videos and he turned out to be quite correct.