> Google charges money (to verify your identity I assume, it's quite cheap) if you wanted to make actual apps for chromecast
It's $5, but just FYI, you don't have to pay or register your app if you make a Default Media Receiver. You don't get on-TV UI, but that's probably fine if you're just transcoding and displaying video.
I made a transcoding proxy for Chromecast, for it to work, I'd have to piggyback the url-player (without selling my identity). I don't like stuff like that.