The dash cam video was only released last week, in conjunction with a lawsuit. Now it's on all the mainstream news outlets, from the Wall Street Journal to the New York Times to Fox News.
This is yet another "Tesla hit slow/stopped vehicle on left of expressway" accident. There are now three of those known, two with video, one fatal. Watch the video. The vehicle is tracking the lane very accurately. Either the driver is very attentive or the lane following system has control. Then, with no slowdown whatsoever, the vehicle plows into a stopped or slow-moving street sweeper.
Here's one of the other crashes in that situation.[1] This was slower, so it wasn't lethal. There's another one where a Tesla on autopilot sideswiped a vehicle stopped at the left side of an expressway.
So don't brake suddenly when unnecessary, only in case of emergency. In other cases just slowdown to full stop and alarm human driver in process, giving him more time to react.
IMHO, emergency braking must be mandatory for every new car with top speed greater than 60 km/h.
Last I heard, nobody has been able to verify if the car was actually in autopilot mode. However, the emergency braking also clearly failed, if the police report that no attempt to stop was made is true.