You can use almost any instant messenger for that including Skype, Google Talk, Windows Live Messenger, Yahoo Messenger or Omegle.

All of these solutions are good. Even if you need to install something, it is not a big problem.

For recording the speakers web-cam and talk, you may use screen video capture software (screen recorder). If you need to record both sides of the talk, make sure the program has such a feature.

Besides screen recorders, you can use programs like Skype recorders.