The Internets and The Google

The Internets and The Google

What is the optimal length for a video communication?
I have heard a few times that a good length for a video communication (streaming video with interactive content) is about 3 minutes. I think the reasoning behind this was that people tend to lose interest and/or click-out if it's much longer. I am looking for some research to back this up, but have been unsuccessful thus far. Can anyone help?

CNN Story about President Bush’s use of “The Internets” and “The Google”. … Bush 43 Internets