My understanding is that the car is randomly braking even when the optional self driving feature isn't used because they attempted to replace a long-time tested radar-based crash avoidance safety system (mandatory in US+EU) with something based on cameras + computer vision because of ... reasons.

Please correct me if I'm wrong.

He is talking about adaptive cruise control, which is a standard feature in 20k cars now(called ACC on Honda Civic or TSS 2 on Toyota Corolla).

"A $70,000 car that can't even do cruise control is inexcusable and so, for now at least, I must recommend against the Model Y."

This wasn't clear to me either in the video or the review.