T203994: Link to a video file page with a specified start time implemented functionality for File pages to link to a specific start/end time of the video. This funcitonality is not discoverable. We should provide some sort of UI to generate links with this offset.
Example: https://commons.wikimedia.org/wiki/File:Ljubljana_Time-lapse_-_Castle_view,_New_Square,_Ljubljanica.webm?start=0:30 should jump to 0:30 when the video starts (except on Mac/iOS Safari).