In the last few years, the landscape of media for youngsters has gone through a transformation. Now kids watch videos on tablets and on their parents phones, and there’s been an explosion of content on YouTube and other social media platforms aimed at little ones. One preschool-teacher-turned-kids-show-host worries about the forces shaping the industry these days, and he’s been talking to a range of kids-media experts to get their advice on a way forward.