Nowdays like many other families we have Netflix on demand, and Amazon on demand. We can browse the screen and pick out the movies that we want to watch. New releases we can watch instantly with a HD copy sent right to us. And that's me, Im 36 years old though. The younger generation grabs their movies and content right off of bit torrent and Pirate Bay for free. That is why Blockbuster videos are closing down. As an aside there is an interesting other reason called Redbox. I'm sure you have all seen these Kiosks around 7/11's and supermarkets. For only 1 dollar a day you can rent new releases if you don't mind the 30 day "windowing" period. I saw one of these Kiosks at the airport in Austin, for a buck you can grab a movie to watch on your laptop and then return it to any Kiosk in the country. And it's totally self service and convenient. Why would anyone want to go to Blockbuster and pay 5 dollars? or even 3 dollars? So price, convenience and selection are killing the "brick and mortar" Blockbuster stores. Hollywood video is already gone, and Blockbuster stores will soon only exist on the internet competing with Netflix, and for a while Redbox.
Barnes and Noble has not "gone under" but they have been put up for sale. I love books and I love browsing in Barnes and Noble. But they have been seriously hurt by the amazing company that is Amazon. People like Amazon for the ease of shopping on their site, the selection that B&N cannot match, and the entire experience. Also millions of people like myself are now choosing to buy their books directly on mobile e reading devices like the Kindle. B&N has tried to compete with Amazon by launching both their own e reading device the "Nook" and their online store at bn.com In both cases they do not offer nearly as good of an experience as Amazon does. I knew this would eventually happen with them, but I didn't think it would happen so fast.
And the bottom line is this, whether you think these changes are good or bad, it is what the consumer wants.