Beware drag and drop of video to folders or desktop
It did not seem to be working despite others saying it did.
I tried with several files, one appeared after several attempts, then others several minutes later.
It dawned on me was it exporting with a conversion applied not actually copying the original?
Yes it was - Canon video clip from 5D II within Photos.
The 'copy' dragged to the home folder:
Timestamp changed, reduced resolution and type file.m4v.
Apple TV, Mac OS X (10.4.8)