Ebert flirts with definitions of art, but never provides his own. This is the biggest problem by far with his essay. Maybe his definition really is something that flat-out can't include videogames. But when he simply says "videogames can't be art" without explaining what he means by art, we can only fill in the blanks with our own definitions. It's no wonder gamers get enraged by this. And they say, "Of course games are art, look at Bioshock/Braid/Flower/etc.!" And Ebert looks at these games not with the gamer's definition of art, but his own, and says, "Of course these are not art."
It's pointless and inflammatory and it can't possibly go anywhere constructive until Ebert defines his terms and explains just what he means when he claims videogames are not art.