maybe the flashback happened b4 Kakashi got the eye, and Itachi was talking about Obito?
and then obito tried killing Kakashi to get the eye, but couldn't defeat Kakashi and lost, and Kakashi decided to take Obito's eye out as a reminder of what happened?
actually, it goes very well with the fact that Kakshi is coming to stop the fight now, as he already knows what the results might be...


anyway, that's my theory, and i'm gonna stick to it.