why would a medium that requires concentration like video games have a detrimental affect on attention span?
In any case, I doubt it's so much that video games are detrimental and more that you ought to have a hobby which actively cultivates concentration.
I remember being a kid and playing games like Tomb Raider where you would have to really think and work hard to unlock puzzles. Even games that offered you the opportunity to just fly through them usually had some form of deeper gameplay. For instance, SF Rush was all about things flashing by really fast, but the real challenge was to collect all the keys in the game, which often required a lot of innovative thinking about finding things to jump off.