What are you talking about miles, I did answer the question to the best of my knowledge. However, following your statement, you didn't either, as you have not provided the OP any information about how to get the video signal from the rear screen/dvd player. Anyway, not to nit pick, there is no simple, this is how you do it answer to this. I have provided the best technical answer that I have avail from years of experience in that field. Each set up is different, there is no certainty that you will even have the same units in two similar vehicles as the vendor for the dvd/screen units may not be the same.
OP, I am sorry if you think that anyone here has not tried to help, but simply put (again) what you are trying to do is not simple or straight forward and there is no "unplug wire A, plug in adaptor B, etc..." answer to this.