It's viewing with actual 3D depth. A flame is first rendered and saved to be, say, your left eye view, then rotated horizontally clockwise and then rendered and saved again for the right eye view. They can then be made a stereo pair or red/cyan anaglyph using a freeware stereo program like Stereo PhotoMaker.

http://stereo.jpn.org/eng/

On this board I found Shood has many examples in his gallery.

http://www.renderosity.com/gallery.ez?ByArtist=Y&Artist=shood

Fractals can be made stereo with any program that allows rotation where you can see the z-depth. Chaoscope does the job, I haven't yet tried XenoDream. Quat has a stereo option in the program. The best way to get a stereo pair is by making a lateral shift, but these fractal programs only seem to allow rotation which seems to work fairly well. The lateral shift method can be used to make stereos in any 3D computer graphics program or with your digital camera for that matter. Hope this helps.

gannon