All these cameras do is pre-select the images that are worthy uploading. Everything else happens at Flock.
That's why they don't give anything about the camera's security.
The images are all from a public place, so no privacy expectations and what's theworst that could happen? Someone uploads their cat images or the pr0n collection?
Ai figures that one out rather quickly.
Assuming the point of these cameras is security (and not just surveillance for stalker cops), being able to upload replacement footage would subvert that entirely. This has been a feature of many spy and cops/robber movies.