I don't think this special episode was actually needed. It doesn't really add to the plot. And the scene or two that are important as background information could have easily been added into the main series. It does eleborate slightly on what Zhang Teng was that upset by Fan Ze Rui being the one that has joined his enemy, but I don't think it really excuses his behavior. Or explains his feelings and why is he this attached to Fan Ze Rui while it appears that two haven't been in contact for very long. The other things were very predictable and not really surprising.