The increase in data from police-worn body cameras can illuminate formerly opaque practices. This article discusses using audiovisual big data from police-worn body cameras, citizen recordings, and other sources to address blind spots in police oversight. Based on body camera policies in America's largest cities, it discusses two possible roadblocks: (1) data retention and deletion, and (2) limits on use for evaluation and discipline. Although recordings are retained for criminal prosecutions, retention for oversight and accountability is overlooked or is contentious. Some departments have no policy on videos concerning civil suits against the police. The retention time for non-evidentiary recordings is also much shorter. Some policies limit their use for evaluation and discipline. Transactional myopia—seeing at the case rather than the systemic level—leads to a focus on specific footage for particular cases, rather than the potential of aggregated body camera big data to reveal important systemic information and to prevent the escalation of problems.