I'm hoping the police and NTSB have guards on the impounded car and they have a strict chain of custody on anything Uber accesses.

To be fair though, Uber can probably extract, and potentially even change this data, remotely. Given their track record, that's not outside the realm of possibility at all. They'd be stupid to attempt it with the world staring at them, but this is also the company that had Greyball, the hell map, blatantly disregarded laws in many countries and had to hire Eric Holder's company to run damage control.

A couple years ago we had the ability to remotely access and modify the recorded video on this platform. Dunno about now.

What was the reason to build that feature?

It's probably easier to just enable ssh on the prototype system to enable arbitrary remote debugging than to specifically design a locked down API for accessing certain data.

Wrong question. This is always going to be possible on preprogrammed cars. Even if they pretend that feature is "locked out".

Alternatively, you're assuming the police on the scene knew how to exract the video from the car without Uber's help?

Edit to add: I don't really think they intentionally darken the image, but this probably isn't even the camera the car runs off of.

I was under the impression this was just footage from an off-the-shelf dashcam. I could figure out how to get video out of mine without an instructions manual. Is that not the case here?

You have no idea where the video came from. Completely conjectural example: uber contacts police (who haven't even tried to find any sd card or download the contents or figure out how to convert it to a format postable on twitter) and says "hey I have the video for you."