The VBR on the codec helps with fast motion, there have been some rough and ready tests posted on other forums where a fast moving shooting situation that “breaks” the HDV codec doesn’t show any problems when shot with the EX1.
The story from Sony is that the XDCam HD codec is more efficient than the HDV codec as it was designed to be used in a broadcast environment. We’ve been shooting XDCam HD for a while and have had no issues. Obviously the EX is packing more information in to the same codec so I’m going to be interested to see how it holds up when we get ours.
I couldn’t tell you any of the technical reasons why the codec is better and to be frank I don’t care, as long as the codec holds up well in real world shooting situations then the theory is irrelevant.
I think the next few weeks will tell as more people get hold of the cameras.