Rigid body collision

I tried to create a rigid body collision simulation based on this tuotorial.

I got totally lost at the point “Now move the cursor to the animated flag and press ‘I’ (this keyframe controls the animated flag)”. I figured out that this is supposed to calculate sphere moves for the rest of the frames, but what the heck is the “animated flag” and how can I control it like shown in the tutorial? Now I had to place the sphere again for each frame.

I’m using Blender 2.79b.

I managed to change the color of the “animated” selection box, but still no effect on the animation.

I have now reduced the keyframes down to 2, but the sphere doesn’t hit the boxes. There’s also a 3rd keyframe (result from fiddling with the “animated” button), but it is a bit of a mystery to me.

Mystery solved!