B_001.mp4 -

: MP4 (MPEG-4 Part 14) is a standard container for audio, video, and text.

: If you see this name in a media player like Plex, the player may be displaying the internal metadata title or the physical file name because it couldn't find a proper movie match. Common Video File Specifications: b_001.mp4

: It is frequently used as a default name in "File Manager" directories on USB drives for generic song or meeting recordings (e.g., B_001.mp4 , B_002.mp4 ). : MP4 (MPEG-4 Part 14) is a standard

Here are the most likely contexts for this specific file name: b_001.mp4