An argument that video games are art was put forward earlier in an excellent post made by my classmate Christopher. The post contains a video that rebukes Roger Ebert's claim that video games can never be art because of their interactivity by pointing out the improvisations that can occur in music, especially in jazz. I would take the argument further. Literature, film, painting and sculpture also require interaction. Even when the artist has a specific message in mind different viewers, readers, and players will make unique interpretations of a piece.
I also believe that the interactivity of video games can be an advantage to them as an art form. You should see some of the totally insane things players have built in games designed for player creation such as Minecraft, LittleBigPlanet, and Spore. Even shooters like Halo and Crysis have produced some cool creations. Click on the links to see some.
The interactivity of video games can also be important when considering a definition of art as a human creation meant to elicit an emotional response. When we watch a good movie we become emotionally invested in the characters. Its why we root for them to overcome their challenges and feel upset if our favorite dies or fails. Consider the emotional impact games such as the Mass Effect Series might have then, games where the player's own choices determine their character's relationship to the others and whether they live or die.
If we consider paintings and sculptures as art, then there is definitely no reason not to regard some of the spectacular visuals provided by video games as art. Below is one of my personal favorites, and I encourage any readers to comment with a link to their own favorite.