Asynchronous delivery
Databeam/Lotus LearningServer http://www.databeam.com/ could become interesting but Lotus itself suffers from lack of clean web integration. Shared files have to be displayed in a whiteboard. Databeam was purchased by Lotus and it is not clear what Databeam Learning Server is. They offer a conference center which uses NetMeeting and FarSite which appears to be shared whiteboard.
Eloquent http://www.eloquent.com has 100 employees and appears to focus on producing and delivering digital video combined with presentations. This is offered as a service.
Microsoft NetShow multimedia delivery from Microsoft
RealNetworks Real Media and many systems built around this technology.