I will add that if you keep it as two buttons, the colors should be switched. Right now, the active button is black and the other is gray. But gray buttons say to me that they are disabled, so it looks like I can only hit the play button when it's already playing.
Full screen streaming works beautifully for me, it's how my wife and I watch Amazon Prime movies. It's just like watching TV. I've read that the computer needs to encode the video it's streaming to the chromecast, so if your computer is slow, the streaming will be slow. That may be why you were getting poor results.
Very nice looking setup. Easy to use (as advertised) and attractive by default. I love the simple look of it.
[edit]Since advice is not forthcoming, I'll add a suggestion instead. A forgot password link would be great on the login page.[/edit]
Oddly, though, I can't log back in. I created an account, made some pages, and signed out. When I try to log in with the email address I used, it correctly changes to my username, but then it says that the username is invalid. Any thoughts? http://d-rock.authpad.com.