Holography entails the diffractive reconstruction of the wavefront corresponding to a 3-D scene, and optical holograms are generated using the coherent interference of light scattered from a 3-D scene with that from a second reference beam. Holography, by definition, necessitates scene reconstruction via diffraction. In the case of an electro-holographic display, diffraction patterns corresponding to 3-D scenes are computed and displayed on suitable light modulators to achieve wavefront reconstruction. This technology is still in its infancy, so you probably won't see anything truly holographic in the marketplace for some number of years.

As cool as this demonstration is, it's using a 19th-century technique -- "Pepper's Ghost" -- and cannot correctly be called holographic.

Here's work out of MIT depicting the true state-of-the-art in real-time electroholography: http://web.mit.edu/newsoffice/2011/video-holography-0124.htm....

Today's average 3D displays are "stereoscopic": they have 2 views, for the left and right eye. A real hologram shows the whole object, so multiple people can walk around it and see it from every angle at once.

But this isn't even stereoscopic. This is just a 2D image reflected on a piece of glass.

I think you need elements of light interference and diffraction for something to be a hologram.

It's essentially a way to "record" light the same way you can record sound in grooves or magnetic tape.