Often MP4 files will have metadata such as titles, comments and other data stored behind the media file. In some cases you'll never notice it, but some media players such as VLC, will use the information like titles and display them. In addition to media players, media organisers like Plex, may also use the metadata information, depending on if "local file information" is treated with a higher priority than indexers like The Movie DB or The TV DB.
Using mp4box
(part of GPAC) provides a way to remove standard metadata information from an MP4 file, essentially rewriting the MP4 container, without modifying the original stream.
This will remove the metadata from the file in place, a file with out_
is created temporarily for the new ISO data to be written, once completed it will overwrite the original source file.