WebinarJam operates using both Javascript and cookies on your system. If you have either of these blocked, the application may not load.
In Google Chrome, go to Preferences > Advanced Settings > Privacy > Content Settings and make sure they look like this:
If the box that the red arrow is pointing to is checked, uncheck it before you attempt to run a webinar. WebinarJam will not work if you don’t accept cookies from our service.
And that’s it! If your Content Settings look the same as these, you should be able to download the WebinarJam application with no problem.