Had the same idea a few years back. You don't need blockchain though, good old fashioned CAs will work. Use standard digital signatures on the keyframe data bu

Had the same idea a few years back. You don't need blockchain though, good old fashioned CAs will work. Use standard digital signatures on the keyframe data but that does necessitate a new video format standard. Good luck with that. You could probably DIY by overlaying a QR code signature on the video keyframe as a stopgap until an official format exists.