Spontaneous Human Invisibility

I read about this a long time ago, where some book I cannot remember mentioned that if you get lost in your thoughts and yourself deeply enough, you become invisible to others. Kind of like a cloak.

Now this article reminded me of this.
I started wondering: If this thing occurs, shouldn’t it have been caught on tape? A quick search on Youtube and similar sites gave nothing, save a few obvious hoaxes.. Not that it means anything if you cannot find it on the Internet.. And then, if it happened, would a camera pick it up or does the invisibility cloak only apply to human observers? That would seem to be the most probable case, since we only see what we want to see, through the filter of our almighty ruler, our brain.
Another mystery of the Soul, the Universe and everything in between.

And here’s a comprehensive guide to achieve invisibility.

(note to self: if you ever feel invisible to others, slap someone hard. That will probably make you very visible very fast..)