Aligning the polar grid north with the antimeridian makes sense for
the *north* polar grid. In particular, doing so makes grid east
correspond with the eastern hemisphere.
Aligning the *antarctic* grid north with the antimeridian makes no
sense to me. I've never heard of anybody doing that, except in the
video we have been discussing: http://www.youtube.com/watch?v=rc4r3a6F0aA
I suspect the video is answering a contrived, unrealistic question.