on vidio Two bulbs on off three places in staircase wiring

staircase wiring is a common multi way switching or two way light switching connection one light two switches wiring that is to operate the load from separate positions such as above or below the staircase from inside or outside of a room or as a two way bed switch etc.
what is a two way switch
two way light switch is a switch that can be used in conjunction with another two way light switch to turn a light or lights on and off from more than one location.

staircase wiring is a common multi way switching or two way light switching connection one light two switches wiring that is to operate the load from separate positions such as above or below the staircase from inside or outside of a room or as a two way bed switch etc.
what is a two way switch
two way light switch is a switch that can be used in conjunction with another two way light switch to turn a light or lights on and off from more than one location.