Too Long; Didn't Read
After almost a month of reconnaissance, we have figured out the Chromecast protocol, and it works flawlessly and reliably! The first job is to make a Sender app and then a virtual connection to the device. The apps accept requests to play, pause, change to the next item in the queue, and other similar commands. We can send messages to open an app, Android apps such as the YouTube app or other “media player apps” either custom made or readily available from Google.