I'll release source soon. I'm going to be open sourcing this app, along with doing a Play release of another app.
This works out of the box... for now. But it's using an app id that probably shouldn't have made it to production. But if that gets shut down, you can host your own whitelisted app id, and that will work fine.
Also, let me know if you can put me in touch with someone from the Chromecast team. I'd like to talk to them about getting production whitelisted.