AP style refresher

Doug Fisher at Common Sense Journalism notes an AP change that may have gone unnoticed in the last update:

DVD -- Now uses disc instead of the odd disk used previously. So it's digital video disc or digital versatile disc if you must spell it out somewhere.

When would you spell it out? Hardly ever, AP says: "The acronym is acceptable in all references in most stories, but spell out somewhere in a story in which the context may not be familiar to readers."