In principle, you can't. The videos involved in criminal cases are evidence of criminal proceedings. Family members, like ordinary people, actually have no legal reason to copy videos. The investigation is based on the principle of confidentiality. At the end of the investigation, the video should be transferred to the procuratorate and then transferred to the people's court after public prosecution. Link to the article: Article 160 of the Criminal Procedure Law 1. The public security organ shall ensure that the facts of the crime are clear, the evidence is true and sufficient, write a prosecution opinion, and transfer it to the people's procuratorate at the same level for examination and decision together with the case file and evidence; At the same time, inform the criminal suspect and his defense lawyer about the transfer of the case.
2. Article 172? If the people's procuratorate believes that the criminal facts of the criminal suspect have been ascertained and the evidence is true and sufficient, and criminal responsibility should be investigated according to law, it shall make a decision to prosecute, file a public prosecution with the people's court in accordance with the provisions of jurisdiction, and transfer the case files and evidence to the people's court.