Migrated from: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/275

The MultimediaViewer class has some configuration options such as preloading distance, which cannot be currently changed before the lightbox is opened, because of the lazy-loading. There should be a way to do that. (For extra points, have a sane configuration class instead of variables littered here and there.)

A similar problem is that there is no way to override/replace methods in MMV, because the instance is only created when the lightbox opens. For wiki administrators / gadget writers trying to modify behavior this will be a problem. Maybe we should just offer a callback for this?