This Flash presentation breaks the large photos into separate Flash movies (.swf's) so that the user may determine the order in which they are loaded. Were they all combined in one Flash movie, the user could not view the last photo without waiting for all other photos to download first.
By breaking content into multiple movies, we let the user control which photo will be the next one sent by the web server. You will notice there is no wait time for a previously-viewd photo to be re-displayed, because once a photo has downloaded it remains in cache.