I grabbed an app called "Avia" which will do streaming of local-to-the-device content. Chromecast support is a $3 in-app (i.e. per-device, not per-account) purchase once you download the app, which is itself free.
It works. Note that the chromecast has very limited codec/container support, so lots of my library has to be transcoded.
It works. Note that the chromecast has very limited codec/container support, so lots of my library has to be transcoded.