I have seen the video previously since I am one of his followers @shaderbits and that ocean is a Gerstner wave type, not FFT. The crest is a mesh with particle emitters on the mesh vertexes, which is not hard since you can procedurally do the placement at random querying for the wave height. The splashes on the rocks is a bit more trickier, you need to map all the places where you want the splash to occur and query wave height at those locations to spawn a particle emitter once there is a match. The feature need to be balanced and used with caution to not kill the framerate.
That effect in a FFT wave will be so much better, since the shapes are great!
In few more weeks I will have something to show, pictures and videos!