Inspect the HTML code of your page. Compare the ViewMedica iframe on your site to the basic iframe code from your ViewMedica.com account.
If you see an attribute or new class injected or added to the ViewMedica On-Demand iframe, there's a good chance a 3rd-party plugin or service is being used.
Example of 3rd-party code injection
Third-party optimization plugins or services can strip the referrer needed for the On-Demand player. This causes ViewMedica Error (VME0010).