It's a peculiarity of the file system NTFS. When a file 4 gb or above is deleted NTFS overwrites the cluster addresses in the MFT with FFs, so the data indeed cannot be found. You may be able to find the file with a deep scan, as it probably still exists on the disk, but this will only return the first fragment. If the file is fragmented, as it may well be, then it is very difficult to recover.
It's a peculiarity of the file system NTFS. When a file 4 gb or above is deleted NTFS overwrites the cluster addresses in the MFT with FFs, so the data indeed cannot be found. You may be able to find the file with a deep scan, as it probably still exists on the disk, but this will only return the first fragment. If the file is fragmented, as it may well be, then it is very difficult to recover.