Sorry didn't see this, but the thread I made was more of a discussion about the specials and I thought this was for youtube videos like those made by SMP Films and such. (Which by the way, Cory Williams who makes SMP Films and the Mean Kitty channel did make a couple of "spooky" episodes called Creature of the Night, and Creatures of the Night featuring his cats.)
Here's the My Little Pony: Friendship is Magic Episode called "Luna Eclipsed" which centers around Princess Luna, the Princess of the Night who's in charge of raising the moon during the night.
http://www.youtube.com/watch?v=_BTN8kTT76Q
The Ponies sort of have their own world, so they call it Nightmare night instead of Halloween, but it's basically the same thing, trick or treating, costumes, candy and pumpkins and such. Even apple bobbing.
To understand what's going on though, I'd suggest watching the first two episodes of season 1, and the series is actually pretty good.
They also have specials for Christmas (Hearth's Warming Eve) and Valintine's (Hearts and Hooves day.)