There are multiple reasons you can receive an error message when watching on a web browser. Here are some of the quick fixes that will help:
The first thing to do is to try to reload the webpage or restart the browser itself.
If this does not work you can try a different browser(preferably with a clean installation) and see if this helps.
Another reason might be an overly aggressive antivirus as Kaspersky. Please close all other tabs and programs and disable your antivirus - the try to watch on FITE again and see if it works.