Flying a drone in the Southern Ocean from a sailing boat in 5 metre waves and 38 knots of wind. Obviously not a Spark, but I'm pretty sure they're using modified Phantoms of some kind.
Some of the footage is not particularly smooth, but you can't blame them considering they're on a moving platform that is wet and bouncing up and down trying to keep that very moving platform in the shot. The catch at the end is pretty impressive too!