'Uncaught TypeError: undefined is not a function' in Chrome (HTML5)

I have a course that when published as HTML5 and uploaded to a server (a must) works fine in Internet Explorer but in Chrome it doesn't play and I get the following error:

This is all the error states. Any idea what could cause it and how to fix it?

The course works fine when played locally so it's an issue when it's on a server - but have tried on a few different ones and no luck.