I've been using the new 2.9.0 beta, and used the Chromecast link to stream a movie from my phone to the TV. It worked great, and I'm very happy that it does on-the-fly transcoding for video formats that aren't normally supported by Chromecast (like mkv).
I had one issue, where I would pause the stream, and after a few minutes I would unlock my phone and unpause the stream. Unfortunately the stream would restart from the beginning of the video. I figured out how to get around this by first disconnecting the Chromecast connection, pausing the video, and rewinding 10 seconds. When it's time to restart the stream, I hit play and then reconnect the Chromecast connection. The video would then resume at the proper position.