@ricardHagerman: This link is pretty pointless for a 4.6.1 web application as it’s a Unity 3.x webplayer. You should install the webplayer you find on this site. The webplayer plugin is always required to download the actual playback engine based on what the content you want to play requires. It’s not ment to manually download those. There’s no offline download.
Make sure you don’t block the access of the webplayer (firewall, noscript, antivirus, …)