I'm quite new to Blender and have been trying to get into camera tracking for my movies for a while now. I have gone on lots of forums and watched many tutorials but can't fix this problem. Whenever I track a scene and simply test it with a cube, the cube starts moving around and spinning about and things like that. I simply don't understand as I'm very new to this. I have got a movie clip off of a YouTube tutorial and tried to add a cube to test it and the same thing happened. I'm not quite sure how else to explain it, but the cube just keeps moving around.
Please help, Thanks.
Here's the file: