What do you see? I see a whole lot less noise, but there's also certainly nothing like the same sharpness. We don't have any details from the poster about fstop, settings, lenses etc. There's a blog page in Japanese about the shoot, but with the google translate I'm afraid I'm not getting any details.
EOS 5D Mark III ISO 12800 MOVIE[tentblogger-vimeo 37879608]
There is however this image of the two cameras side by side:
(cover photo credit: snap from the video)