I think what is needed is not just a player, but some software that can pull out a set of files, possibly by time, display video, speed, time, position and maybe a map, then turn this all into a straightforward video that might, just might, be acceptable by court, police or insurance organisations. It would also be good to have this able to take the files off the phone and present them similarly.
As far as I can see, all the individual software to do this exists - it's just a case of someone writing the complete version.
It ought to be ddPai themselves, of course, and I think everyone should keep pushing this to them. The hardware is good, good Windows and Mac software would be a massive selling point. I'm too old and out of date to write software anymore, but I have done serious beta testing in the past, and would be prepared to do so again.
Their social software may be fun in China, but I take my daughter to work every day, and every day my "Driving score" is penalised when I go through the same double roundabout with a hairpin after it. What is the point of that? Do they not have sharp turns in China?