JD-EE and CogSim,
At this stage I wouldn't put much weight on what we know of crew interactions (i.e. one crew member acknowledging or not acknowledging another's words). The words of the crew released by BEA would have been selected to provide some context (not all by any means) to assist us (the public) in understanding the most basic aspects of what happened. The how's and why's are still a long way off.
In the last 10 mins of the flight -- especially the last four -- we can be certain there was a great deal of crew interaction.