Displacement mapping, I suppose, is more important to movies, because this way the basic view of the model is all the animators have to work with, compared to the millions of polys that could come from the original high poly model, as well as lagging the 3D animation program out due to the high amount of polys, as well as textures. Paralax mapping is commonly used in types of textures like on the one above. Here's another example: animated water in games. You could use an animated normal map or paralax map, along with programming the game to position some foamy bubbles whereever the player/object lands, to give it a good enough look (as well as the waves). Then there's another way, but it is a poly killer. You could try making you water using a matrix (and in case you don't know, which you probably do know, a matrix is pretty much a flat 3D grid of polys) that you can program to act like water. This, when given a side view, works wonders. Evolved's water shader is a perfect example of a poly saving water shader:
I must say, Evolved has quite a gift for these types of shaders, he's made a good collection, and these shaders are in fact very useful. Also, a paralax map works great with lighting. I recommend using normal maps for details that aren't that great in depth, wheras a paralax map works better with larger object illusions and lighting. Take a look at this (Evolved's Paralax mapping shader:
As you can see, in the front view, it looks completely 3D, but when you look at it from the side, this effect is pretty much ruined (the effect is ruined even more when paralax mapping on objects with a flat appearance). Hoped we helped, cheers.
Typos, they can't live without me.
