The course is made up of five sections that show how to create apps that support both Google Cast as well as building native Android TV apps. Most of the course does seem to discuss Android TV specifically, which makes sense as it requires more development. Still, the course description explains why developers should look at the TV:
By adding Google Cast functionality to your app, you can increase engagements and monetization. For example, Comedy Central found that Chromecast users watch 50 percent more videos and make 1.5 more visits to their app, than their average users. Likewise, Haystack TV found that Android TV users watched 80 minutes of video per week, vs. just 40 for mobile-only users. The best part for developers is that both Google Cast and Android TV come with extensive libraries that do most of the heavy lifting for you.
This is one section of the Ubiquitous Computing series, which includes courses for Android Wear and Android Auto development as well.