The Beaver was landing on what is called glassy water. This is where there is no wind, and the surface of the water is like a mirror. Under these conditions there is no depth perception and it is preferable to set up an approach using power and reduced flap and 'drag' the airplane in in a slight nose up attitude until it touches down. I forget the whole story behind the Beaver accident but rigpiggy is essentially correct. The company decided to use one of their own hot shots - who I seem to remember had a brand new float endorsement - instead of an experienced pilot, with the results you see there.
The correct procedure for a glassy water approach with the Beaver is to use climb flap and enough power to maintain 70 - 75 mph in a slight nose-up attitude with about a 300 fpm rate of descent. (I seem to recall about 20 -22 inches of manifold pressure and 1800 RPM.) The airplane will actually begin to round itself out as you enter ground effect. The touchdown should be just forward of the float step, with the heels of the floats about parallel to the surface of the water. In the video the pilot touches down in too level an attitude and the airplane goes squirrely on him. He appears to try and correct the yaw at which point he ceases to be a pilot and is now along for the ride.
I won't comment on the second video. I've never flown a Goose, but if the guy is as good a pilot as it is said, I guess he had a bad day As an old friend once told me, "Sometimes you bite the bear and sometimes the bear bites you."
