A system and method for determining proximity of individuals to specific regions of interest such as Point of Sale (“POS”) terminals within a POS monitored area of a scene of video data captured from security cameras as part of a networked security system, when the security cameras are located outside the POS monitored area, mounted on a ceiling or other high location and pointed at the POS monitored area. With the help of customer regions drawn in an abstract layer whose areas coincide with expected locations of individuals near POS terminals in the video data, and video analytics elements such as bounding boxes generated around individuals in the video data, the system can perform live and forensic analysis of the video data to infer information such as the proximity of individuals to POS terminals and the relative height of an individual compared to their expected height within the scene of video data.