Heads up. Google's latest Chromecast update intentionally breaks AllCast. They disabled 'video_playback' support from the ChromeCast application.
Given that this is the second time they've purposefully removed/disabled[1] the ability to play media from external sources, it confirms some of my suspicions that I have had about the Chromecast developer program:
The policy seems to be a heavy handed approach, where only approved content will be played through the device. The Chromecast will probably not be indie developer friendly. The Google TV team will likely only whitelist media companies.
I'd strongly suggest holding off on buying a Chromecast until we can see how Google chooses to move forward on third party applications. There are also other (open) platforms and stacks that one could buy/support as well. (LeapCast, NodeCast, etc)