I have Xperia ZR with 5.1.1 LP. I also have BubbleUPnP pro installed but when I try to stream a recorded video (full HD) to Chromecast it plays, then stops, and plays, then stops again...
If its not a natively supported format by chromecast than bubbleupnp transcodes it locally. So u need powerful device to be able to do that on the wifi and good signal. Especially if u use dlna or streaming from local server.