This is likely a production code. In digital media archiving, "BST" often refers to a specific studio or series label. You can search this specific string on media databases like The Movie Database (TMDb) or IMDb to see if it matches a cataloged entry.
You can use ExifTool to view the internal metadata of the file, which may reveal the original creation date, the software used to encode it, or the actual title of the content. 4horlover___BST297.mp4
Because there is no "paper" or formal documentation available for this specific file string, I have provided a breakdown of how to identify the content and what the alphanumeric codes might signify. 🔍 Identifying the File This is likely a production code