Use a 3D software player?
The two side by side films are meant to be a separate image for each eye (that's how 3D works).
The files need either a software player that works with them, like sview or bino, or a 3DTV.
I'm gonna guess you didn't read the 3D tutorial linked on the main page of the site?
Here's the link to it... viewtopic.php?f=35&t=72246&p=196665#p196665
Please don't hesitate to ask more questions if you have them!