If it's the same video I saw, it was the ankle guy. And yeah, when it comes to historical cases of chess cheating (almost always at a lower skill level) they'll either use some form of chess computer that they sneak away to use, or have an accomplice and a one way method of communication.
Another thing to keep in mind is that often times players at this level don't need to cheat every move, they just need to be given the correct move at an important moment and they'll be good enough to understand why they are being told to do that.