On the other hand, the reason that a Blu-ray Disc player can play DVDs is that manufacturers decided to make sure that all Blu-ray Disc player include both blue and red laser assemblies, so that they can play both Blu-ray Discs and DVDs. When you place a DVD into a Blu-ray Disc player, the Blu-ray Disc player activates the proper laser assembly in order to read the DVD. In addition, when you place a CD into a Blu-ray Disc player, the same red laser assembly that is used to read DVDs is refocused to read the CD.
The good part to all this is that if you don't have a Blu-ray Disc player, you don't have to spend the extra money for the Blu-ray Disc version of a movie. Of course, the bad news is that if you have a Blu-ray Disc player in your main room and one or two DVD players in other parts of the house, you will have to buy both the Blu-ray and DVD versions of the movie if you want the full benefits of both formats.
However, to assist in solving this problem, more studios are releasing combo packs that include both a Blu-ray Disc and DVD version of a movie in the same package. Another option being used on a more limited basis are so-called "flipper discs", which have a Blu-ray version on one side and DVD version on the other side on the same disc.