FreeConferenceCall company has published new version of their video conferencing application that aims at one-presenter-thousands-viewers video conferences and screen sharing.
Their application works on Windows and OS X and uses solely Sciter based UI with extensive use of Sciter’s unique popup DOM elements. Even video is rendered by Sciter with custom native video frames providers.
It is probably hard to realize, but that bar on the top and popup from it is HTML/CSS in reality.