Video allows for interpretation of what is going on in the environment of other participants. Perhaps this is a side-effect of a generation that grew up with television. Most desktop videoconferencing applications have a shared whiteboard capability. In the lecture environment, it is very helpful to have a good view of the speaker's written materials. In conference mode, feedback on visual materials such as annotations is very useful.
Application sharing is another useful feature of desktop videoconferencing.
A common example used to illustrate this capability is participants collaboratively editing a spreadsheet or word processor document. It takes time to compress video and audio and transmit it. This lag can contribute to a loss of interactivity experienced with videoconferencing systems. There is a learning curve involved with effectively utilizing new tools. Some people are not yet computer literate and may be wary of using desktop videoconferencing.