I'm late to the pop-culture party (as usual). Though it's a little disturbing to watch, I can't look away:
The dots on the guitar neck are visual references. They help you jump to a different part of the neck quickly, easily, and with accuracy.
For example, if you were playing Tunnels by the Arcade Fire, you might play a power chord on the 1st fret followed by a power chord on the 10th fret. The dots, being visual references, make a nine fret jump a bit easier.
The rest of this post will go over all the details of the dots on a guitar neck, what they mean, and how you can use them to augment your guitar fun. Let's hit it...
Oh me, oh my...
To grossly over-simplify, guitar pickups are permanent magnets that are coiled with copper embedded underneath the guitar strings on your guitar.
These coiled magnets create a magnetic field which then detects disturbances in the movements of the strings and transfers that signal to an amp.
If your eyes are glazing over, I empathize. Seriously, I do. The rest of this post will clear up the mystery of guitar pickups. Let's hit it.