ABSTRACT
Since a few years ago developers have been increasing the number of applications and services that offer to their users the possibility of establishing videoconference sessions of multiple users through a web portal. Some of these systems allow the recording of their sessions. We can find examples of these portals such as WebEx 1 , FlashMeeting 2 or Marte [172]. On the other hand, during this period some Internet portals have arisen to allow the users to upload their own recorded videos of lessons, conferences, etc. In these other portals the videos can also be accompanied with slides or presentations that have been used in the session. Examples of these services are Youtube 3 , RTV-Doc 4 or iTunesU 5 .
