Mechanical reproduction techniques have taken theatre and condensed it into a frame as big as your television screen. It was the most obvious and natural transition, I think, to have some of the first films based on great works of theatre (Walter Benjamin mentions A Midsummer’s Night Dream). Benjamin discusses the ways which theatre is different than film, even though both deal with the same core aspects (storyline, actors, change of time). He attributes this change to the way that art has become more technologically inclined, and the way culture has found different mediums to express the same “pure” art.
He talks about the fact that in theatre, there is audience, and that the actors have to deal with the fourth wall in an environment where there is an immediate response form the audience, whereas in film, the acting is done directly to camera. He talks about the concept of time and space, and how in theatre this is achieved by set and lighting design, whereas in film this is made possible with different camera angles, and post-production techniques.
He does, however, say that this new “mechanical reproduction” is estranged, that film is impersonal, and the new techniques that are used in film “render superficial and insignificant any possible similarity between a scene in the studio and one on the stage.”
Seeing as this is written in 1935, where cinema was still new and flourishing, it is understandable that his views are not consistent with the views on cinema now. Even though cinema was originally based on theatre, they are both different art forms. I guess it will just take time for “new plagiaristic remixes” to become new legitimate art forms.