normally a switch like this comes with 3 prongs,
two for switch operation (open and close circuit),
another one is for ground (for the light on/off indication)
the prongs location might differ depends on manufacturer.
however for this rocker switch,
the 1st prong (left in this video) must be connected to power (wire from +ve battery),
2nd prong (middle) goes to your accessory,
3rd prong (right) you can ignore this if you want, as the switch is already in action if you had connected the first two, however there will be no on/off light indicator though..
if you want the indicator turned on when the switch is on (close circuit), connect the 3rd prong to ground or your -ve battery terminal. (be sure to connect the first two prongs correctly) otherwise the light will not give correct on/off indication (as shown in the video)
