This can help you reset or change the blocked or allowed website that use plugins.
New Linux bug gives root on all major distros, exploit released In this video we show you how to manage your google chrome plugin exceptions. Chrome is at the latest version on both computers. For more information and instructions, see the documentation from Zotero. I tested the site with chrome from another computer and it works fine. Zotero now has a Google Docs plugin, which works in the same way as the Word plugin, but relies on having the browser extension(s) installed, not on a separate installation.
I looked at the source and they have mp4 first then webm. Strangely I can play HTML5 video on other websites (with the same computer/browser).