Moving MP4 files results in TMP disk thrashes

[ic1male]

I've noticed on Windows 8/8.1 that if I move MP4 video files, rather than just move the file directly, Windows copies the contents to a TMP in the new location, renames that TMP file to MP4 and then deletes the original. Why is it doing this? Anyone know? If it's a move on the same drive, it causes the HDD to thrash like mad whilst it does this MP4>TMP>MP4 process for every single moved file.