I think the point is that, insofar as video game or entertainment software is a medium, it's a very versatile one in terms of format. Video games can resemble traditional games, movies, novels, table-talk RPGs... and lots more. Surely this versatility is a defining characteristic of the medium, and I don't see why anyone would want to limit it by, for instance, implying either that movie-like games (with a focus on graphics, sound and story) should not exist or that all games should have movie-like elements.
Going to expand on this later.