Late binding closures in this code

Question

I came across this code which is one of Python's gotchas:

def create_multipliers():
    return [lambda x : i * x for i in range(5)]
for multiplier in create_multipliers():
    print multiplier(2)

I read the solution here but I am confused at some places. I have two questions:

1. Why is it printing 8,8,8,8,8 instead of 0,2,4,6,8?

2. They come up with this solution

   def create_multipliers():
       return [lambda x, i=i : i * x for i in range(5)]
   

   What is i=i doing and why it used?