The first step is to insure the chromecast is all setup properly. Can you view other videos on your chromecast through your browser? You must also use the Chrome browser with the Chromecast extension. Once you have Chromecast setup in chrome and you can watch other videos you should be able to watch intelivideo just the same.
Before we go further. Can you watch other videos and/or view your browser tabs? If not; you've got to get Chromecast setup first.