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We utilize the open source jQuery RTE plugin (http://www.intrepidstudios.com/projects/jquery-rich-text-editor/documentation.aspx) to provide basic rich-test editing capability (along with significant modifications of our own to provide the video-sync highlights and better feedback).
We use Ben Alman's hashchange jQuery plugin (http://benalman.com/projects/jquery-hashchange-plugin/).
We also use jQuery (http://jquery.com/) and jQuery UI (http://jqueryui.com/).