Any chopper pilots that can attest to the alleged risk shown in the video?
Not a pilot, but I've ridden in them enough and talked to their pilots enough (and okay, I have some "unofficial" hours of flight time) to help explain a little bit of what happened.
All aircraft, fixed or rotor wing, fly best in cooler air because the air is more dense and the wing gets better lift. Keep in mind that the best air for lift is "undisturbed" air. Vortices (horizontal "corkscrew" patterns of disturbed air) left from preceding fixed-wing aircraft, and the "doughnut" pattern of air movement created by a spinning helicopter rotor (you see this a lot in the movies when a helicopter flies through smoke) are all "disturbed" air and make it harder for the wing or rotor to get lift.
When a helicopter first takes off, it is in that "doughnut" pattern of air and it is harder to get lift, but once it starts moving forward, the air is "clean" or undisturbed, and the lift is better. In this case, the helicopters had done just the opposite - they had gone into a hover and had lost the "clean" air that once helped them to stay aloft. This in and of itself wouldn't make a helicopter go down as long as the pilot is taking into account the disturbed air and adds "power and pitch" (explained below.) Now, add to the situation the fact that higher temperatures (higher temps equal less dense air) make for even lower lift... and then add to the equation that the aircraft over water is in a higher humidity environment which in turn further decrease the density of the air, the ability of the wing or rotor to produce lift, and to some extent decrease the power made by the aircraft engine. You can see what is starting to happen here. Aircraft can be very tempermental when it comes to temperature and air density. There is an old saying that altitude is your friend, in that it gives you time to correct mistakes. In this case, they had very little altitude. But I would be willing to bet that the pitch control (controls the amount of "bite" that the rotor takes out of the air) is bent upward, and there is a lot more slack in the throttle control (engine power) than there was earlier that day. Someone had to have yanked straight up on the pitch and given the helicpoter all the throttle it had - and they pretty much kept it on a straight line with the pedals while they were doing it. I can't condone the actions that got the helicopters wet, but I do have to say that it was one heck of a recovery...
Aircraft can throw you for a loop every now and then if you don't keep your wits about you. You have to be observant of not only everything that is going on with your aircraft, but also the type of terrain over which you are flying. At 500 feet, I've been bumped up an additional 200-250 feet above ground level just by flying over a big asphalt parking lot - the heat can provide a sudden updraft. I've "ridden the roller coaster" on days when, from the ground, all would seem calm - just the difference between flying over pastures and then flying over wooded areas. I've also lost friends that had their aircraft suffer "catastrophic airframe failure" when they dropped 2000 feet in a matter of seconds due to sudden changes in the atmosphere (27,000 AGL to 25,000AGL in 19 seconds in an AeroCommander - the wreckage was strewn over 5 miles.)
The main thing here is that no lives were lost... Anytime someone damages an aircraft to that extent, the instructor pilot is held responsible for the situation and has to stand tall before the man. It's just the way it is... If the two instructors are really as good at piloting as the recoveries indicate, I would say that they will be back on instructor duty as soon as the dust settles and the publicity dies down. I do not believe this was some "stunt" but rather some miscalculation on the part of both student and instructor. Anytime you have a helicopter hit the water that hard, you run the risk of having it "roll over" and then it's the end. The recoveries were indeed pretty awesome.
Regards,
Raven6