I would agree, if the Autopilot didn't need a significant amount of human attention to avoid a simple, potentially deadly crash. Your equation should be rewritten to:

human paying attention to driving + human preventing Autopilot from crashing + Autopilot

I seriously doubt this divided attention produces a safer system with today's technology. Except

> but we need to compare those against the cases where autopilot prevents accidents that are unlikely to be avoided by humans

Right, but do any examples of this exist, ever?

Your link is clearly not an example. Any aware driver would've done the same.

I'm sceptical there can ever be a scenario were tesla autopilot can outdo an aware, conscious driver.

Some of the examples in the video are actually pretty impressive. I'm not sure I would have seen some of these cars coming. But they only show that human driver with autopilot assist is potentially better than human alone, i.e. human driver, with autopilot backup. I would be surprised if that is not better. But the way autopilot is supposed to be used is that it's only autopilot with human backup. And I would argue that the "with human backup" often has a "because of law, not necessity" undertone)