The Mythbusters set out to prove if the special brace position while on a plane was a good position to protect yourself. Well, yes, it is, but which was the safest place on the plane, and what is the best position you could be in?
The Mythbusters were a bit puzzled on how they would set out to experiment with this. They said they could use a plane, but they would only have one shot at using a plane. So, they used a simulator - They dropped a similar model to a plane (made out of wood and metal ramps) as high as 15 feet, using test dummies the first time, of course. The dummies ended up with torn off limbs - Just the legs, though. The fact is, if you didn't protect yourself, you shouldn't put your feet under the seat in front of you, and worse yet, you shouldn't do nothing. If you did nothing, you'd break your neck as soon as the plane would hit the water - But the brace position was designed to prevent that fate, and keep you alive. When the Mythbusters were done experimenting, though, they weren't heppy. They needed real people, not dummies. Three of the Mythbusters bravely stepped forward, and accepted the task. They were about 10 feet up instead of 15 feet for their safety, though. Luckily, the Mythbusters team survived because of the brace position. Back at the lab, though, they were doing some other tests. In the end, they proved that the brace position, and buying First Class tickets could save your life. It turns out that the flight attendant's seat is the most safest of all on planes, though. The Mythbusters proved that the people at the back of the plane were in the most danger, as they would be killed by the flying debris from the back of the crashing plane. The people at the front, however, were under the most protection, because their seats were more spaced out, meaning they couldn't break their neck upon landing on a seat in front of them. Therefore, the Mythbusters had become successful in their experiment.
Thus, the Mythbusters proved that the brace position and First Class tickets could save your life - And that the flight attendant's area and seat were the safest part of the plane.
Be careful with that word, "Proved". Mythbusters has given some evidence that such is true, but they have proved nothing.
And that evidence, from your description, is shotty at best. Every plane is different, made out of different materials and constructed in a different way. There is no reason to believe what is true for one plane is true for all. Also, what they set up, as you said, was a model. There is no accurate way to test if the model is accurate. It gives a good idea, but like I said, is shotty at best.
There is footage of a plane landing on water. The plane was hijacked in Africa and ordered to fly to Australia by some idiots who wouldn't believe the pilots when they said it couldn't get there on 5 hours of fuel. So the pilots did the best they could - aimed for an island. The plane ran out of fuel and the pilots attempted to land it near a beach. It actually looked to be going well, then a wing/jet touched the water and the plane broke apart. This was captured on film by someone on the beach. Tourists swam out, took boats etc, but only about 1/3rd of the passengers survived.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman