Currently, you need to write your own media player to support adaptive bitrate streaming on Chromecast.
Unfortunately, the MS test server assets do not correctly provide a CORS header, which would be needed if you wrote a javascript player.
PlayReady and Windvine are both supported. We'll be providing additional documentation shortly.
EDIT We announced the beta of the Cast Media Player Library today 2/3/14 - it supports HLS, SmoothStreaming, and MPEG Dash.