You wouldn't lose privacy by using a blockchain if the file is encrypted. It is protective, because the time of upload can't be faked with a blockchain. As I stated, one could prerecord and upload at a later time, thus faking the register to make an event appear more recent than it really is, but once uploaded, there is no way to falsify the recording has having happened at a later point in time than the upload. If these recordings are being streamed in real time non-stop, the recordings can be assumed to always reflect reality, thus providing strong evidence in court.