This gap is here to allow you to see the text tool bar for the header bar below. When site is published, the gap will disappear
The presence of -5- before the extension is unusual. Most naming conventions place part numbers before the extension without hyphens. This could indicate:
ARCHIVE-FHD-SONE-460 -5-.mp4 appears to be a filename for a Full HD (FHD) video file. Below is a practical, informative guide to help you understand, manage, and work with this file effectively. ARCHIVE-FHD-SONE-460 -5-.mp4