I think the parking services only make sense if a) if you have hundreds of domains and want to manage them all at once with minimal effort, b) you want to have them listed for sale (e.g. parking with Sedo helps you sell with them). Otherwise, if you have just a few domains, you are better off building your own "parking pages". There are scripts available that can put up a page of keyword relevant videos for example. You can set up sites like this in minutes. Of course then you have to pay for hosting.