*disclaimer* Im not a pilot, aviation professional or journalist */disclaimer*
The helicopter that went down is a Mil Mi-14 Haze, which is the amphibious version of the Mi-8 Hip. Therefor a water landing is nothing out of the ordinary, it was designed for such task. Much like the better known Sea King.
The Haze has a different landing gear then the Hip. The aft wheels retract into the boat like fuselage, while the front gear fold forward into the fuselage, but outside the boat like hull.
I can find no information about the seaworthyness, ecspecially in regards to wave height of the Mi-14 Haze. But if the info is correct about an engine failure at t/o this must put quite a heavy strain on the remaining engine.