A lot has been written about the supposed synergies across the "three" video screens: TV, online-connected PCs and mobile, hand-held devices. This week, I'd like to talk about an interesting connection with a fourth: digital, out-of-home screens. Actually, in this case, I'm really talking about a multitude of screens: screens on airplanes, screens in supermarkets, and even screens on gas station pumps. What do they all have in common? Well, they're all screen-based affiliates of CBS Outernet, the digital out-of-home division of CBS Corp. that reaches millions of out-of-home viewers each month. What else do they have in common? They're all teaming up to help with a potentially disruptive transition of another screen-based medium: television.