That's actually not true. It can do nothing about M of N cryptography. (That's when a key is broken up such that there are N parts, and at least M (less than N) are required to decrypt. It doesn't matter how many rubber hoses you have, one person can fully divulge or give access to their key and it's still safe.
I always giggle a little when really smart people forget thugs exist and do what they’re told. If that includes breaking the knees of M people to get what they’re after, then M pairs of knees are gonna get destroyed.
This isn’t hard to understand, but it’s easy to forget our civilization hangs by a thread more often than any of us care to admit.
I don't remember the provenance of the quip, but somewhere at a def con or a hope, I heard, "The point of cryptography is to force the government to torture you."
They're perfectly ok with that, and depending on where you live this may happen in more or less overt ways. If the government wants your information, they will get your information. Your very best outcome is to simply rot in detention until you cough up your keys.
Now that I think about it, I'm pretty sure it was a session about root zone security, and Adam Langley was in the room. I was thinking, damn, kinda sucks to be the guy that holds Google's private keys. They want someone's information, so they let you rot...
You know there are other ways to have a video and send it to people than YouTube, right? You can just email a link from dropbox or gdrive, or an attachment, or send a WhatsApp/Telegram/etc. message, send a letter with a USB drive, etc.
Bob, Jon, and Tom have pieces of the key. Bob and Jon are in the US and arrested over and commanded by a court to give up the key. Tom is the holdout. The US will issue an international arrest warrant, and now Tom can never safely fly again or the plane will be diverted to the nearest US friendly airport where they will be extradited. So, yea, "safe" is very situational here.
This probably works if each person has a cyanide+happy drug pill or a grenade and is willing to sacrifice themselves and the rubber-hoser(s). I think that requires a rare level of devotion. This process must also disable a simple and fragile signalling device to let the others know what's coming.