If store B is actually the black market then you actually did steal from the one producing whatever you bought or possibly from store A.
What do you mean by your first sentence? I am fairly sure that movies do actually cost quite a lot to produce.
What do you mean by your first sentence? I am fairly sure that movies do actually cost quite a lot to produce.
That does not even matter since looking at marginal cost of a movie makes no sense. Do you want to see movies? If yes then pay for them, if no then simply don't watch them. Justifying stealing isn't the way to go.