Stereoscopic Player is a great free software to play 3d movies.
It allows you to play stereoscopic videos and DVDs (external decoder required) and also allows you to watch live video from a capture device. Since it is based on DirectShow, it can handle almost any media format, for example AVI, MPEG, WMV and ASF. Videos can be coded in several different stereoscopic formats.
A link to download: Stereoscopic Player More Infos: 3D Player
At the same site You can download Stereoscopic Multiplexer that captures stereoscopic video from two separate cameras. You might use the Stereoscopic Multiplexer. It combines video data from DV camcorders, Firewire or USB webcams and most other capture hardware to a single stream in side-by-side format. It can be used within Stereoscopic Player as well as third party video software that supports WDM capture devices, for example Windows Media Encoder.
More infos: Stereoscopic Multiplexer