Download of AirStreamer 1.6 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This Mac application is a product of ATKSOFT. AirStreamer for Mac lies within Audio & Video Tools, more precisely Players.
From the developer:
AirStreamer enables playing MKV, AVI, and WMV videos on a Chromecast device. All you need to do is turn on your TV and Google Chromecast device and make sure your Mac and Google Chromecast are connected to the same IPv4 Wi-Fi network. Then, you can open your video files by clicking on the menu File -> Open from AirStreamer and wait a few seconds for the video to play back. AirStreamer does not support DRM-protected files.
You may want to check out more Mac applications, such as AirStreamer Lite or AirStream, which might be similar to AirStreamer.