40489a9a - Mp4 Thumbs Jpg

: Short for "thumbnails." These are low-resolution preview images created so your device doesn't have to load the entire video file just to show a preview icon.

: Indicates the original source format of the video from which the thumbnail was extracted. 40489A9A Mp4 Thumbs jpg

These files are cache files. If you delete them, your device will simply regenerate them the next time you browse your folders. Deleting them is a common way to clear up "Other" or "System" storage space on mobile devices. : Short for "thumbnails