I have the same issue. Technicaly the bypass does work but the system only checks the state of the parking brake when you switch to a video source and not as soon as you turn the unit on. I had a discussion with the guys at microbypass and this is what he said exacly:
Hello. I have confirmed that you are correct. The reason why this happens, Is in the programming software, the radio does not look at the state of the parking brake wire at turn on. If the unit is in FM, or even CD mode, and you load a dvd, The radio must be powered off then on to have the correct delay on the parking brake wire