Chris Anderson's list of faltering mainstream media includes under 'mixed':
DVDs: sales growth is slowing dramatically, from 29% last year to single digits this year.
Hang on a second there, that isn't a fall, it's a dip in the 2nd derivative - if it grew 29% last year and ~ 10% this year, it's still doing well. Notice also that the linked article mentions that studios have been shortening the wait between cinematic and DVD release. Think about the impact that has - it moves DVD sales earlier, thus giving an artificial short-term boost that will eventually even out.