__hdbb14014.mp4 -

: Many security cameras (CCTV), dashcams, and bodycams use alphanumeric strings to catalog clips by date or device ID.

: Some messaging apps or video editing software generate temporary file names like this while downloading or rendering content. __HDbb14014.mp4

This specific naming convention—starting with double underscores followed by a mix of letters and numbers—is typical of: : Many security cameras (CCTV), dashcams, and bodycams