Mr. Ebert is incorrect for the very reason that the medium does not determine art.
Writing is often used with an objective - to communicate inventory, describe an actual scene, give orders.
Rhythm and rhyming may be used to aid in memorization, to aid in oral recollection.
Pictures, video are used for documentation, recorded evidence.
Wood, marble, steel is shaped to create buildings, stairs, chairs, eating utensils or religious relics.
Bodies move with precision in order to build, cook, or fight.
Interactive computer programs and simulations exist to educate, train, provide guided assistance on tasks, or obtain information.
At some point we get art out of all these mediums. We decorate the urn, make our religious icons more elaborate, tweak our oral histories to make them more fun to listen to, arrange our photo shots, play with the beats, create a more elaborate melody. The medium changes from straight functionality more and more to creation for aesthetics, to elicit an emotional response rather than a strict material/practical goal.
For me this point in video games (interactive computer programs and simulations), was definitely reached when playing "Planescape: Torment" back in the early 2000's. Yes, ostensibly you have a clear goal, and you can win the game. But the dialog and overall plot elements are such that I was immersed in thought, absorbed by the characterization and concepts. For others in my rough age group (cutting our teeth in the mid 80's to 90's) it may be games like "Myst" or "Psychonauts", Infocom's "Trinity", "Grim Fandango", or even a silly satire like Mystery Science Theater 3000 Presents "Detective" (http://www.wurb.com/if/game/146); more modern might be Katamari Damacy. Yes, please get off my lawn all you newfangled Xbox360 and Nintendo DS gamers.
If someone's never had an aesthetic moment with a video game it simply means that they haven't found that game yet.