Was Mr Ebert right? Are games just "mental masturbation"?

He's right, masturbation is known to call upon the brain's reflexes, depth perception, and problem-solving skills the same way playing video games does.
I'm glad Ebert finally put his Neuroscience degree to good use.

Seriously though, I think people gave this way more attention than it really deserved. Ebert said the same thing about videogames that any typical snob would. Yet people went out of their way to either vilify him or try to make videogames (or give examples of already existing videogames) that would appease people like him, simply because he was Roger Ebert. As much experience as he had with movies, he was completely out of his element when it came to videogames.

Even if you ignore his complete lack of experience or knowledge of videogames, Roger Ebert had his own idea of what art was and videogames didn't fit the description. I have my own idea of what art is and while videogames can pretty much fit the description, something like Slam Poetry might not. Different forms of expression mean different things to different people, what is or isn't art isn't a matter of fact but more a matter of opinion. Most people already know this by now, so I don't see why so many people gave one guy's uneducated opinion so much attention.

As scipioafricanus said, Ebert's views were more open in earlier years. For example, he reviewed the game Cosmology of Kyoto in the 90s and had no trouble enjoying it and its artistic achievements. Here's the link.

Besides, Ebert was a film critic; I don't know why people would put so much importance on his view on games. I mean, I've seen some people who are literary theorists and have a very pejorative view of cinema in general (hell, I myself would put literature, games and modern tv series as art forms superior to most movies), so it's not uncommon that people who are specialized in one art view other arts as minor.

We should also remember that Mr. Ebert was a reviewer and a very good one, but not a theorist. This is a huge difference, and basically means his writings on art look, at best, as informed opinions - nothing backed by a solid research and useful theoretical concepts. So, I would neither put much weight on his opinions about games or art in general - it's fun to read them, but they just aren't very deep.

I dunno. I like the idea of critiquing these kind of opinions. He was so anti-video game that it was just downright hilarious.

He struck me as one of those old fart types who hates new forms of art/entertainment, and his lack of knowledge on the subject matter (games), coupled with his hypocrisy regarding animation as an art form (he considered many CG movies art, and yet games are essentially CG too, except games usually have better art direction than Pixar/Dreamworks films), makes his "analysis" of the medium fun to tear apart, IMO.