Ever wanted to make a fun 3D video? This is how!

[edit] Things You'll Need

[edit] Warnings

The slightest angle difference in the cameras will completely ruin the whole shot. Make sure the lenses are level with one another.

Check the "Things You'll Need" Section. Get your two cameras, and make sure the lenses are 2-8 (three works best, but the greater the more 3D effect) inches apart. It helps to create a device that holds them both from the tripod screw spots on the bottom.
Film whatever you want in 3D with both cameras.
Upload both videos into your video editor.
Make one of the videos (let's say the left camera's video) have a red overlay. Make the right camera's video have a blue overlay. The result should be the same video, twice, in two colors, three inches apart.
Place both videos into your editor, on top of each other, so you can see them both at once. The result should be almost purple and you should have a somewhat "double-vision" look to it.
Export this video, and play it, while wearing those Red-Blue 3D glasses and it should work. If not, you should try experimenting with the settings.
If need be, switch the colors to darker or lighter shades. Maybe even try changing the distance of the lenses.
Make sure you can "Place both videos on top of each other" with whatever "simple" editing software you have

You must make sure that your two videos are in exact sync with each other, otherwise you will get a poor result.
When editing these videos together, it also sometimes helps to remove the audio from one of the videos.
While recording, the cameras must be perfectly aligned. Check if they are aligned with a level.