When the narrator talks about improvements in Radiant AI, he gives as an example two NPCs fighting over an item dropped by the player character. In the official sources, that example is given as something done through http://www.gameinformer.com/games/the_elder_scrolls_v_skyrim/b/xbox360/archive/2011/01/17/the-technology-behind-elder-scrolls-v-skyrim.aspx, never as something that happens through Radiant AI. As I said, some of what he says doesn't quite match what I have already heard from sources I trust more. The video is a nice-looking, well-delivered, and fairly accurate presentation, but I would not take everything it says for truth.
In http://www.oxm.co.uk/26155/bethesdas-todd-howard-on-elder-scrolls-5-skyrim/ article Todd Howard describes a scenario while bringing up both Radiant AI and Story. To me it seemed to illustrate the interaction between the two systems. In the specific scenario the weapon could be returned to due to radiant AI, and then the quest could still be available due to Radiant Story. I realize now that it's unclear which would be governing the situation though.
You're right though, I can't believe I overlooked that information in the game informer article. At least the information is true though, and the event's were only attributed to a different system.