Side by side is when no filtering is applied to the original left and right movie. Two video streams are projected next to eachother (or the one above the other).
This method is perfect for all kinds of 3D TV's!
Nothing from the original movies gets 'lost in translation'. No filters, no reducing the refresh rate, nothing, period! You can see the movie with a special technique without any hardware (crosseyed method).
Because you have both unaltered video streams at your disposal, it's quite easy to convert side-by-side porn movies to any other kinds of 3D porn (anaglyph, shutter,…). Visit the software section for more info
Little hard to use the cross-eyed method.