[jdietrich]

>at least the video would be verifiable

Nope, it'll just give well-executed fakes a veneer of legitimacy. A state-level actor will have easy access to the signing keys. Non-state-level actors could potentially extract them from a device or bribe an engineer at a third-tier Chinese OEM. A reasonably competent hardware hacker could desolder the CCD from a signed device and feed whatever video signal they like into it.