Firefox:
In order to disable the protection in Firefox, click on the shield to the left of the URL in your browser and choose "disable protection on this page" and wait for it to reload.

Chrome:
Click the shield shape to the right of the url and click the link that reads "Load Unsafe Script." Wait for the page to reload.

Internet Explorer:
When you navigate to the preview page in Internet Explorer, a small box will appear at the bottom of your screen. Click the button that says "Show All Content."