There are two pieces of software i want to link to, both of them are free!
Stereoscopic player is a must-have tool for the stereoscopic porn surfer. It's made to play any kind of 3D, and even convert one techique to an other one (only if the source movie contains enough information to be converted to the destination format offcourse…).
The program is easy to work with, but if you can't figure it out, HERE is a FAQ.
VLC is an easy FREE tool to replace windows media player. Only use this one when you're watching a pre-rendered movie (for example, when you downloaded an anaglyph porn movie).
The tool itself is great because it's faster, and more stable than windows media player. But in the end, you can always use media player if you don't want to download VLC