That's the way I was leaning on this one, but,

I saw the the problem was not getting the files onto a Flash Drive, invariably formatted as FAT32, but getting it onto a Windows 8 laptop which is almost certainly formatted as NTFS.

I don't know this for a fact, but I doubt that Win8 can even be installed on a FAT32 formatted disk.

My conclusion, and I'm so glad you all asked, is that the 64GB Flash Drive is corrupt and is reporting that the file size of those movies is in excess of 1TB to Windows.

Reformat the Flash Drive, NOT the laptop, load up the movies again and give it another shot.