That proves nothing. It could be showing the original codec and not the background transcoded file.
We won't know until it's released and reviewed.
Larry Jordan - who was at the original, fabled demo, at Supermeet, questioned the engineers, and originally broke the story that FCPX even existed - is stating it as FACT on his blog. His questions are how FCPX transcodes the final output AFTER editing, and that's a genuine unknown.