Resume Views tracks user progress through third-party Browser Cookies. A viewer's progress and ability to resume their view to a presentation will be retained in the browser for as long as those cookies remain in the browser’s cache. The default size of the cache will vary depending upon which browser they are using.
If the cache is cleared or if cookies are disabled in the browser, Brainshark will not be able to resume the viewer to where they last left off. The viewer will also be unable to resume their view to a presentation if they switch browsers in between sessions or changes which machine they are working on.
Here’s an article going over best practices when using cookies in Brainshark: