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Haha I wouldn't trust that with a ten foot pole (does that make any sense? Probably not).
Here's the thing. In order for a video to go viral, it has to have a couple of important qualities.
1) It has to be truly compelling content. Content that people will look at and say 'oh, well so-and-so has to see this', or 'my friends would really think this was funny' or 'I want Reddit karma so I'm going to repost this tomorrow (or in an hour) as my own find'.
2) It has to have broad appeal. It can't be niche. The broader the appeal, the better the chances of it going viral. That excludes almost every single gaming video, and almost every single vlogging video, just to name a couple of examples. It also excludes great sports plays (which never go truly viral), many cute kid videos, and most cute animal videos. It really has to have that broad appeal to truly go viral.
If a video truly has those two qualities, then you're already 80% there. The rest is putting it in front of as many people as possible because at that point it doesn't matter because everyone is a targeted lead (mass appeal). If you have that kind of content and pay one of those services, and it reaches the front page of Reddit, for example, for even an hour or two, there is a good chance it will end up going viral. If you don't have that kind of content, all the promotion in the world won't make it go viral.