Inconsistent Error in Firefox for running WebGL Builds

[Dynamoid_Megan]

I am attempting to make a build of this project: GitHub - hecomi/Unity-WebGL-3D-Chat: Unity5 WebGL x Socket.IO = Online 3D Chat on the web browser!
I am able to run other WebGL builds from local files that I created from other Unity projects. Other WebGL builds run in the same browser, (Firefox 41.0) , but when I try to run a build of the WebGL 3D Chat program, I get an error telling me to use another browser.

It seems your browser does not support running Unity WebGL content from file:// urls. Please upload it to an http server, or try a different browser.

Why would that be?

[jonas-echterhoff_1]

Is there anything else in the console? The error it shows is obviously not correct - we use this error message as a fallback for errors in file:// urls, as we cannot precisely detect the error when using file:// urls in browsers which don’t support it, and it is one of the most common issues for first time users. But this means we get some false positives, where we show this message, but the real error is something else.

[Zoelovezle]

@jonas echterhoff

Is there anything else in the console? The error it shows is obviously not correct - we use this error message as a fallback for errors in file:// urls, as we cannot precisely detect the error when using file:// urls in browsers which don’t support it, and it is one of the most common issues for first time users. But this means we get some false positives, where we show this message, but the real error is something else.

I tried the same project on his own demo page and my website by customizing few lines in script (www.skyies.com/Games/demo/web/unity) .
I essentially found the error loading socket.io.js .I am not sure how to fix this .

BrowsersTried : Google Chrome , Safari , Mozilla Firefox , Developer Mozilla Firefox

He is getting the error since the project needs to be on a hosted website to run .