Perhaps "FG" refers to an educational software platform (e.g., "Future Generation"). In the late 1990s and early 2000s, educational CDs were ubiquitous. This bin might contain dozens of .avi or .mov files documenting historical events, scientific phenomena, or geographical surveys. Because they were labeled "optional," they might have been left off the main installation to save disk space, destined for a separate folder that users could install if they had the hard drive capacity.
: Short for "binary" or "storage bin." It denotes a low-level repository or an execution path where raw media inputs are temporarily cached, indexed, or staged. Architectural Implementation fgoptionaldocumentaryvideosbin