The thing is -- let's assume the video's pre-recorded, because it'd be silly not to. So a detailed tutorial on "how to open your Circuits if you have any" gets posted on the internet.
Let's say 1% of the viewers believe it, and of those 1% succeed. If we start from an audience of around ten million people - and popular Youtube videos get way more than that - that's on the order of a few thousand people. Scattered all over the world, no particular way to track them - maybe a few families have precog or scrying, but they'll be massively outnumbered.
And then they start doing stunts. Sure, magecraft is hard, but they don't need to succeed to do things that are blatantly impossible. Someone touches a brick, Reinforces it wrong, the brick crumbles to dust - and they do it on live television. Only takes one for that first 1% figure to skyrocket.
No. If the MA want to keep their Mysteries in the face of an internet threat, their only real hope is trying to find an anti-memetic Mystery - some sort of information control spell that can target "a secret" and keep it safe. And that sort of thing is easily in the "one step from Sorcery" tier.
The risk of the above, more than anything, is what will bring them to the negotiating table. They're not going to be certain it's possible - but they'll be uncertain enough that they can leverage it as part of a contract.
First problem is the "detailed tutorial" bit. Even in the online game with the System Assist, it is
rather difficult to open your circuits. Practically everyone needed multiple attempts to try out different modes of thought and method to see what worked, and both the failed and successful attempts were
painful.
So the question is, if
you, personally, found an online tutorial about magic, would you
a) watch it the whole way through,
b) follow the instructions closely enough to have a chance of succeeding, and
c) try two or three or five more times after the first attempt was unpleasant when you have no guarantee that even doing it right would actually provide the promised powers?
If you answered yes, then put your money where your mouth is, find something similar (even if it isn't the F/SN) online, and do it two or three times.
Pain? Sacrificing a chicken? Drawing out intricate patterns in chalk? Dancing and chanting skyclad at midnight? We have no more reason to assume that there is or isn't a Masquerade in our real world than a character in the story does.
If not, then why would you expect any of the mundane people in the story to? Why would the MA feel threatened when most people naturally ignore all but the most blatant and life-altering exposures of magic as trickery?
Second problem is the 1% of 1% of 10 million. If it is a detailed tutorial, fewer people will probably be interested in sitting through it to begin with unless you spice it up. Also, a lot of Youtube video views are, as far as I know, repeats, because people like to watch and rewatch and revisit their favorite videos. So while it may get a lot of views, chances are (to my knowledge, I'm less than sure about this bit) that on average any one person might view it four or five times. So it will be a lot less likely to get to the numbers you're assuming.
Third, the "scattered all over the world, no particular way to track them... And then they start doing stunts." Anyone untrained and unaided is more likely to hurt or kill themselves using magic, and internet instructions would have to include instructions on Reinforcement, etc., for this to be a viable possibility.
In the game, with the System Assist, it still takes average people days or weeks to get magic working, and they tend to hurt themselves trying. That holds true with the System Assist making it easier and while they are in a world where they already know that magic demonstrably works, and they may be in
immediate danger of dying if they
don't learn magic because there are monsters and they need to escape the game. In the real world most of that 1% of 1% would be more likely to give it up after getting hurt, and they have no immediate need for magic in their lives to prompt them otherwise.
I suppose my point here is that the people with the natural willpower, drive, and mental state to make magic work well in the game are also the type of people unlikely to bother with watching the tutorial (since magic doesn't exist as far as they know) and repeatedly trying an unpleasant/harmful activity after being burned once.
Then, if people do start using magic, they've opened themselves up to being scried for by magic use trackers. If they do something big or complicated enough, then they run the risk of being tracked. If they don't then there's little to no risk of exposure.
Fourth problem is with "and they do it on live television". How do they get on live television and practice magecraft? How many people watch that release when it's live? Because it's only live the first time, and after that there can be claims of doctoring, of film edits... and what other news would be going on that would cover this up?
Then how do you prove it wasn't a trick? Prove that the brick wasn't doctored ahead of time to fall apart? Prove that the camera crew weren't in on it all and paid off?
Fifth problem is preventing the M.A. from claiming that it was a trick, the brick was doctored, the camera crew were in on it... If anyone is audacious enough, they can actually bring another (undoctored) brick onto live TV, claim that they doctored it the way they say the first performer did, and crumble it with reinforcement as 'proof'.
Furthermore, the M.A. has resources and ties to companies and political groups across the world. If, prior to the game, Griselda came across magecraft instructions on the internet and mentioned them in passing to Grimlock, what would happen?
1) Grimlock would convince (or if he were more like most magi, hypnotize) her into dropping the subject after she showed them to him.
2) Grimlock would report it to the Magus Association.
3) The Magus Association would bribe, blackmail, or hypnotize people in places of power to shut down the website and hand over information on who put it up.
4) Sic the enforcers on whoever put up the information.
5) Have people keep an eye on the news for a few weeks to see if anyone tries to repeat this. send the enforcers to disappear/hyponotize them and other hired professionals to discredit them if so. If not, no worries.
...
Sorry if this seems aggressive. You actually got me very interested in the idea of how someone would pull this type of thing off, and I just started listing off the problems so that I could move on to figuring out how to get around them. It really is an interesting idea.
Ultimately, though, I think Kayaba's plan has a good chance of working. Technically, it could work now. He could turn the game off, free the several thousand people in it, and it would make a worldwide splash across the news that the victims were free.
Eventually, just out of muscle-memory habit and (maybe) nostalgia, one or two people would try to use the game's magic in the real world. And they would get that familiar feeling and realize that magic is real.
There would still be enough news activity that reports would spread
fast, and other survivors would try the same thing and get the same results, and then there would be thousands of people needed to disappear with more news spreading to millions more. The M.A. could probably kill the survivors and fake 'health issues' leftover from being in the game, but even that would be insanely suspicious and people who hadn't been showing off as much could write down what they remembered, teach friends and family, and it would never totally go away no matter what the M.A. did.
.) Outside interference (like Rin) or bullshit (like Ilya) can still manage to affect the game some, but it's very difficult.
