Buyer B now can a)buy it.
a.1) maybe depending on where they live, with widely ranging prices
a.2) maybe depending on their operating system, player, method of connectivity
a.3) be prompted to install all kinds of weird shit to make it work.
a.4) still have it not work, or have it downgraded to low-def
a.5) not be able to play it on 2 different devices because of strange producer whims.
a.6) have the manufacture stop supporting whatever odd DRM after some amount of time
d) Steal it for one price
d.1) anywhere in the world
d.2) use it on any operating system, player, or method of connectivity they transcode it to
d.3) use their standard player of choice
d.4) have it just work
d.5) play it on 2 different devices
d.6) never have to worry about DRM.
Some people are always going to violate copyright on media, not much you can do about that. The rest of them want a cheap, easy, and fair way of getting your product. Itunes with all its bullshit DRM has shown that if you make it easy, people will buy. People are creatures of laziness, going out and pirating stuff is just hard enough that easy to use services like Netflix make it not worthwhile. Successful producers are going to have to realize the 20th century is gone, in the 21st century the world is globally connected. Putting up little 'content' walls is laughable.
For me the situation is simple: Adapt or die.