In the FAQ it mentions:
If the Media decode error happens in the beginning of playback, then Browser doesn’t support a particular encoding. Check the video and audio formats supported by your browser.
Solutions:
Use the encoding format supported by your browser.
Force the Flash Player.
I am getting a Media Decode Error with MP4’s which I previously played with no problem in flash in my own player. How does one “Force Flash” when they do not play in the Wowza Player naturally?