Nowadays, digital media is important for Amazon. Even though 70% of its revenue was from physical form of books, DVDs, and CDs last year, and when Amazon first started to offer online download service, it did not have big affect on other DVD sellers, but in these months, those sellers' income are cut. Because DVDs and online music download service are substitutes, so if the demand for one of them increased, the sale of the other one will fall.
In my own point of view, download music, movies, and e-books from online will become more and more important for both the customers and the online service providers. For us, the customers, we save time because we don't need to go out and buy stuff; also, download service saves us place, instead of all physical books, CDs, and DVDs, the only thing we need is a removable hard disk. Therefore, opportunity cost for watching a movie become less.
As the "price" of a movie decrease, the quantity demand of it may increase. So, the download service providers will collect more money from provide this kind of service. At the same time, this service help them to save the operation cost because those employees who used to send out goods that customers ordered from online are not necessary any more, and after they cut those people, they have more money to develop other services. The more services they provide, the more benefit customers can get.
So, will you purchase a DVD or download the same movie from online?