@belfegor: What I know is that Volumetric lines can be used for laser beam, what that has to do with the particles engine?
They're also useful for elongating particles to simulate motion blur of particles moving faster than the frame-rate can depict.
Edit: The posted video was rendered in Blender which can simulate motion blur during the render process. For a real-time application such as a game, however, such motion blur tricks as Blender uses might not be feasible. In that case, you can use elongation of the particles to fake it.