Imovie update won't complete and/or leave the update list

I have OSX 10.8.2 and imovie 9.0.8 but can't get an imovie update to update and vacate the list. In the list it says 9.0.8 update: "addresses an issue related to third party Quicktime third party components that could prevent imovie from opening". If it's updated, why is it still on the list and if it hasn't updated, why not considering I've updated numerous things without a problem and yet it's still there holding firm?