Web browsers are designed to retain certain information about the websites you visit e.g., the server(s) it spoke to get there, the content to display, etc. This enables faster content display of previously visited sites, but if the browser becomes confused by something regarding a website it will not display as desired.
Even if two sites display similar content for the viewer e.g., videos, pictures or sound files, etc. the backends (which general viewers cannot see or access) may be completely different between the two sites, even if they are both UniSA owned sites.
Clearing your browser cache is a version of spring-cleaning for browsers, it will help improve the speed and display of websites which are experiencing issues. It will force the website to re-establish communication between your device and hosting server(s). This will refresh the content of the website and enable your device to display it correctly.
Step-by-step instructions (including screenshots) for all browsers can be found on the wikiHow site.
Otherwise, the process for the four most common browsers (IE11, Firefox, Chrome, and Safari) can be found on the clearing the cache page.