I suspect the timing is just like when things are specifically timed right before Christmas - WB is hoping to cash in on last minute impulse buying when the spirit of the season is its highest.
Scroll down to post# 33 for the cover "art."http://www.hometheaterforum.com/t/322116/whv-press-release-house-of-dark-shadows-and-night-of-dark-shadows-dvd/30#post_3947554
But who buys a Christmas special the day before Christmas?
I see NO MENTION of the new movie on the covers? Wow. Wonder if it will be incorporated somewhere else in their marketing. If not, that is telling.