3d Movie without 3D glasses

Do you know that it is possible to watch 3D movies without the 3D glasses? It is a technique that called 'Cross-eyed'. Here's a tutorial on how to do 'cross-eyed' technique...






And..after you master this technique, you can view many more 3d cross-eyed movie in youtube...
Example:


and also..you will able to see the image inside this...




If you are wondering, the image inside is a coil spring (^^)