The YouTube Video Scam is not very common, but is probably one of the most dangerous scams.
The scammer will ask and/or beg a person wearing expensive armour (usually god armour) to be in a YouTube video with him or her pking them, also asking you to only bring 3 parts of your armour so that even if the co-star did die, you would still have what you were wearing. Up to now the player usually would trust the scammer and go to the wildy, though most players are smart enough to recognize that this is luring. The scammer will pretend that the victim really is on YouTube by the scammer telling the victim to say "Oh nooo plz!!", or "Don't kill me!!!", or something similar. But at first he will weaken the victim and they will drop or trade three items, or something close to expensive, but not as expensive as the armour the victim is wearing. When the victim picks it up the scammer will kill the victim.
An example of how this scam makes a profit is the trading of 4 noted dragon battleaxes to somebody using an abyssal whip (when whip prices are sufficiently high). It relies on trading or dropping items with a higher store price but a lower street price. Any such trade or drop should be declined or ignored.
This lure/scam is now obsolete, as items kept on death are now determined by their Grand Exchange values rather than their alchemy values. Thus, in the above example, the victim would keep their whip and 3 of the noted battleaxes.