If it's one of the few that requires a CC # guarantee, which apparently this one you mentioned is, then your CC will be charged - sometimes it's $10 per adult and $5 per child, or in the case of Hoop Dee Doo Review, I believe your credit card may be charged the full amount if you don't cancel and don't show up. However, your dining plan credits will only be charged if you choose to pay with them when you're at the restaurant.
The restaurants that don't require a CC guarantee (which is most of them) will not penalize you in any way if you don't show up and don't cancel. It is nicer to cancel if you're not going to be there, so that someone else can have a shot at it, but even if you don't, there won't be any repercussions to you.