Doesn’t do as it says

It says on the main graphic on the App Store that it plays all sorts of video files, including MKV.
However, when I try to play MKV files, the error it gives is:
"Audio Codec Unsupported – We are not able to process this file as its audio stream uses a proprietary codec.”
Use the Chrome extension called “Videostream for Google Chromecast” instead. It works perfectly, and it’s free.

My nickname is Yochi about VideoCast for ChromeCast, v1.4