Now why do you suppose they chose a series resistance equal to the phones impedance? You don't suppose it could have anything to do with the fact that matched impedance gives maximum energy transfer do you? So now they make sure that any electro-mechanical effects are at their absolute worst. As a matter of interest increase the source impedance more and you move into firmly into current drive mode which has all sorts of implications.
Also, by reducing the source impedance to near zero, in the first place you are 'shorting out' any voltage fluctuations, so of course it looks better. You don't get much voltage developed over zero ohms no matter how much energy you pump into it. Also in real terms you haven't increased the damping factor by the figure given. Due to the high phones impedance still being there you've really only doubled it.
I notice they made no attempt to monitor the acoustic output from the phones. I feel confident this would tell a very different story. Bung a 500Hz square wave in and see how much difference to overshoot is made by their supposedly massive damping. I can tell you now, it won't be a lot.
Finally, they are using their own 'research' to promote their own product. Can you say conflict of interest?
It wasn't me!
(Well, actually, it probably was)