I see a lot of comments about how this is "opt-in". By definition, all of the videos that officers can see the existence of through this portal exist on Ring's

I see a lot of comments about how this is "opt-in". By definition, all of the videos that officers can see the existence of through this portal exist on Ring's servers, not on some individually-owned machine. So if you decline to "share" your video with the police, they can just request it from Ring, who won't and can't decline to share. You won't be notified.