Why is the USB flash drive in exFAT format with sufficient memory, but it cannot copy 5G video?

The USB flash drive will be formatted after the factory, and the default file system is FAT32. A single file in this file system cannot be larger than 4 GB, that is, for a movie larger than 4 GB, this file system cannot be stored unless you divide the file into multiple small files under 4 GB.
 
The file systems we currently use are mainly fat32 and NTFS, and for U disks, there is also an exFAT fast FAT file system. This file system has the advantages of FAT 3 AI, and can also store files larger than 4 GB for a single file like the NTFS file system, so under normal circumstances, you should be able to copy videos, pictures, and data files larger than 4 GB to the U disk using the exFAT file system, of course, provided that the USB flash drive has the capacity to hold this file.
 
The U disk uses the exFAT file system, the memory capacity is sufficient, if it cannot be copied, it is very likely that the capacity of the USB disk is indeed not as large as the capacity of the video, such as the video is 5.1 GB, and the U disk may have 5.09 GB left, which is obviously not able to be placed. Please make sure that the USB flash drive has space greater than the total video capacity, and make sure that the hard disk is normal and not an expansion disk.