Can I watch 3D movies on my Mac?
According to this Apple document:


  
    Autodesk’s FBX for QuickTime enables QuickTime as a 3D viewing solution that supports content from any professional 3D package. With FBX for QuickTime, digital artists can share, view, and interact with 3D content seamlessly, efficiently, and at no cost. Now available for both Mac OS X and Windows.
  


So, I'm guessing that's a yes.

If you want to take that 3D movie and convert it to 2D, you can most likely use MPEG Streamclip for that.