Not really, there isn't a presumption of guilt because first you must establish spoliation. Once it has been established that the video record is incomplete, it

Not really, there isn't a presumption of guilt because first you must establish spoliation. Once it has been established that the video record is incomplete, it must be the duty of the police to provide evidence of the technical failing that allowed it to happen to clear them of wrongdoing. After all, the evidence was in their care. Even if it was simply negligence and not malice.