I'm having a hard time understanding how an optocoupler works. I made a circuit based on example 15 if the Arduino projects book. Instead of trying to hack a button, I'm trying to just light an LED on either side of the optocoupler. I'm misunderstanding how this should work because the LED I'm trying to light doesn't light.

My [youtube video shows my circuit][1]. You can see the blue LED which runs from pin 2 of the optocoupler into ground lights up, but the red LED (which works, I verified) which runs from pins 4 to pin 5 of the optocoupler does not. I was under the impression that if I emitted high from the arduino to the pin 1 of the optocoupler through a 220 resistor (mine is 270 actually) and provided a path to ground that the optocoupler would be switched on and I would get current and ground from the pins on the other side. 

Any suggestions - what am I missing?


  [1]: http://www.youtube.com/watch?v=YL7gv9uQxRQ