1. Users opt to share video clips
2. Police can't view unshared videos without requesting
3. The whole thing is opt-in
I don't see an issue here. It's a technical framework around something that already exists: police going door-to-door and asking for video clips. Why not make this more efficient?
I can see the potential for abuse, as it is all centralized. But I think "portal for mass surveillance" is a bit of an exaggeration.