I'm pretty sure Frenchie saw the door opening, as that car had just parked there and opened the door before Frenchie's car passed it. Since Frenchie didn't comment on the door at all, I don't think it was that close. I think it was at least 1-2 feet between the door and Frenchie's car. I do agree it was a bit too fast.
FSD beta did see the driver though, as a pedestrian displayed on the visualization. Right now, FSD beta doesn't display anything for open doors, but it does take them into consideration, as we've seen in many other instances.
You can see how deceptive wide angle cameras are in this frame immediately after the door incident, where it looks like the car is inches away from the green container:
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