saronian wrote:While I can load .mp4 movie files, only the audio plays, not the video.
In the USA, it's illegal to play movies on the screen visible to the driver while not in park. You can hack the system to enable it. Whether you do or not is up to you. You will get a ticket if a law enforcement person happens to see it, though. You need to recode the car to make that happen. The dealership won't perform that for you, as I said, it is illegal, and they won't be part of it.
A few cars have a fancy screen that lets the front passenger watch a video while it being blocked to the driver (I think it's available in some MB).