When we took my DS to Disney when he was almost 3 (about 2 years ago) I got for him "Disney's Sing Along Songs:
Disneyland Fun - It's a Small World". It was recommended to me from someone's post on this discussion board.
It was great - not only did it get him excited for the trip, it also prepared him for the characters (how big they are in comparison to his size). Even though it is filmed at Disneyland (and not Disneywold) it shows kids running around and singing and going on the rides, I don't think my son would ever know the difference. I just want to warn you, although I don't know how old your kids are, to just look out for the Haunted Mansion song. It really is relatively tame and it doesn't bother my DS now, but when he younger he didn't like it. Also, I think that the video was taped in the late 1980's or early 1990's so to us it looks dated, but to kids it just looks like a lot of fun.
I bought mine (2 years ago), and have also seen it recently, at my local Toys R Us. I also just checked
Amazon and they sell it there as well for about $10. You could probably get one on ebay if you wanted to go that route.
I have passed this tip onto friends of mine and their kids loved the video, hope it works for you as well!!