Previously we shared that Koushik Dutta was working on a way to stream video to your Chromecast device from your smartphone. This was previously not an option, but could be coming very soon. "Koush" just shared a new video and took things a bit further. He demonstrated streaming video to the Chromecast from any media app, while running his custom CyanogenMod ROM.

Here's a quote from him on the subject and you can see the new video above,

Chromecast all the things? That's actually possible.

I added some framework extensions to +CyanogenMod to let any app which plays audio/video using the MediaPlayer to be sent to the Chromecast.

This supports both local content (stuff on the SD Card) and remote content (podcasts).
Source: via Google+ - Koushik Dutta