: Files related to 3D modeling or CNC machining of a "solid piece" of metal or plastic.
Based on the structure of the filename, here is what can be inferred: 38511-91 911531481498_Sub_f_1532173254.mp4
: Automated CCTV exports often use long numerical strings and "Sub" (sub-stream) suffixes. : Files related to 3D modeling or CNC
: The string 1532173254 corresponds to a Unix timestamp for July 21, 2018 . 38511-91 911531481498_Sub_f_1532173254.mp4