As soon as Google unveiled Chromecast, I was lucky enough to scoop up a couple of the $35 devices to connect the two TVs in our home. After a few weeks, it’s fundamentally changed how my family watches TV. It’s also changed some of my perceptions about the evolution of the “second screen.” Most of the TV viewing in our house is dominated by our kids. Ages 3 and 5, they immediately grasped how to “cast” their Netflix shows from our phones (iPhone and Nexus 4) and iPads to either TV. After all, they were already watching Netflix on their...