I think the rule at the WSOP is silly. A protected hand is simple, it is a hand that has not been mucked.
The video linked to by OP, is a classic example of a wrongly mucked hand. Player in a seat next to the dealer, dealer nervous and inexperienced, cards not capped, a busy environment (noise, cameras etc.) The reason this hand was mucked is because the dealer brain farted and mucked the hand. The players hand was reasonably protected, she pushed all in, and her cards were in front of her tight against the rail. No more chips were in front of her, plenty of feed back for the dealer not to have a good reason to touch the cards. This was a dealer fail and the hand should not of been mucked. The outcome was bad, the hand was not retrievable. lots of bad things may have happened because of it, like perhaps the dealer lost his job, the player was shaken up and not able to recover, an embarrassing video made it to YouTube.
All the WSOP did here was offer a rule that allows the hand to be retrieved, a common remedy in most venues but a remedy that has a lot of issues with it, as demonstrated in a long string of comments to 3N1GM4 answer. No one ever wants to get to the point were the decision is dead hand because of dealer error.
However, in any system that is dependent on humans always behaving rationally and predictably to avoid failure, your not going to avoid failure.
The problem with the rule in question (108) is that it is simple good advice, and not a rule at all. If it was actually a rule, you have a dead hand if your hand is not protected. According to that rule as written, as a player or a dealer I can reach over and kill any unprotected hand. It is a silly attempt to codify that "things can happen" and you can have a dead hand. And in doing so they put in an unintentional loophole. I say again, a protected hand is a hand that has not been mucked or more specifically conceded by the player, and add further at this point that anybody other then the player of the hand mucking the hand is in error. The rule is just silly and bloated and should not go beyond simply saying that a wrongly mucked hand may be retrieved if possible.
Back to the video, because this incident is classic in the sense that it encompasses most everything that goes wrong when a hand is wrongly mucked. I think it is clearly established that the dealer was the main cause of the hand being wrongly mucked however, there are so many things here that would of helped this mistake from ever happening in the first place that are not necessarily within the domain of the dealer.
Starting with the player; Mistakes happen! the more you are aware of this, the less you will suffer from these mistakes. The more barrier there is between your hand and the dealer the less likely it is that your hand is going to be wrongly mucked. It would of been less likely a hand gets mucked if the hand is capped by a chip or something else. The player pushed the chips toward the middle of the table, removing another barrier to the hand. The player could of stated all in, leaving the chips in place and lessened the likelihood of the hand being mucked. The more experience a player gets, the more situational awareness they have, the less likely they are to have a hand wrongly mucked. You do have to own this because in the end you are the one with the downside not anybody else.
With the WSOP there was failure on a few levels. Training, hiring and the table layout were all less then optimal to minimize the likelihood of a hand being wrongly mucked. The WSOP chooses instead to have a silly rule act as a catch all, leaving the burden to the player rather then owning their part of game security.
If a dealer says I dealt the WSOP I am not impressed at all. To staff a major tournament they need to find a couple thousand out of work or under employed people that know how to deal poker at some level. You will find the full spectrum of dealers ranging from the very worst to the very best. So there is a lot of potential for dealer mistakes.
There is not a lot of training. It is very basic stuff consisting of short meetings before shift and perhaps some orientation before the tournament starts. Most things covered are things like were you go on breaks, parking and rather or not you rake a pot if there is no flop. I am pretty sure they do not emphasize that you do not take players hands, you let players muck there hands. Even on a regular job in a poker room they will make the assumption that a dealer knows this. There is only so much you can do in the way of training for temporary employees.
The table was a tournament table. It lacks drop slots which act as a barrier that offers a little protection for the player. It did not have betting lines. Betting lines are great to protect a hand. If the hand is behind the line it is protected, if it is over the line muck it. If a player is to lame to get their cards and place them behind the line, muck them. Lines make it all so much more plain and simple.
Rule 108 is a vain attempt to address a problem that is better addressed with other means. While it usually is dealer error that gets a hand wrongly mucked, players that are aware do not get hands mucked that they did not intend to have mucked. I think defining a protected hand the way it is in 108 does not really fit with reality, IE silly. Does nothing to protect players, does nothing to help players protect themselves, just does nothing to lesson the likelihood of the occurrence. The rule at best gives the WSOP some protection from a claim that the dealer was cheating or from a player claiming foul that they suffered a monetary lose.