EDIT: picture: http://imgur.com/a/ceoVh

I just started learning about this and I'm slightly confused and would appreciate if someone could explain this for me. In this video, he ends up using KCL to solve that I1 = 3.333A I2 = 3.333A and I3 = -3.333A. My understanding of this is that this means that the direction of the loop of current for loop 3 needs to be reversed, but what does that actually mean? Because wouldn't changing the direction of loop 3 also mess with the directions of loop 1 and loop 2 which are correct? Can someone draw the "correct" diagram or explain what that means?

Also on the circuit, he has currents like (I1-I2) and (I1-I2-I3). Does this mean that at those places there is 0A or -3.333A of current? How is that possible?