The most common reason is that Flash player is not installed on your computer or mobile device. Click Here to download Flash player.
Additionally, the videos may not be loading due to your connection speed. This system requires a DSL/Broadband Internet connection with a minimum of 1 Mbps.
Disabling the HD option on the video player can also improve video playback performance.
You can disable HD playback by clicking the HD button in the video play bar, that appears like this
When HD is in color, it is enabled, when it is grey it is disabled.