Want Chromecast video from sources other than approved apps like YouTube? Videostream has a solution for the Chrome browser and Chromebooks.
Videostream is a handy app for Google Chromecast users that will project any video file on to the big screen from PC or Mac. File types supported include mkv, avi, mp4, and more. Previously, video sharing has been limited to what you can see on a Chrome browser plus usual-suspect apps such as YouTube and Netflix.
How does it work? Just install the app, open it in your Chrome internet browser, then choose a video file to play from anywhere on your computer; it'll be beamed to the Chromecast dongle stuck in an HDMI slot on your television.
There's also a premium subscription version which costs $1.49 a year and lets you create video playlists and have control via an Android app. The core Videostream app is free, however, at the Chrome Web Store.