I think video games are art but it's a whole new type of art that older generations have yet to accept also because of the costs it was rather impossible to produce a decent game for the sake of just art(money had to be made). But both of these obstacles are diminishing more and more as time goes by.
What makes video games so much more different than other art is that it is the first art to implement the dimension of the challenge/interaction. Music is the art of sound, lyrics add the art of thought to that. Photography/drawing is the art of still visuals, movies adds the art of movement to that, dialog adds the art of thought to that art, music can then add another dimension of art to a movie. But video games is the first one to take all of those arts and add the dimension of challenge/interaction. Challenge and interaction may appear in other things such as sports/games and such but in no other forms before has anything encompassed sound, thought, video and challenge/interaction all in the same medium. It's the next step in the evolution of art.