Look....I just tend to believe that a man flipping a guy off in front of many schoolchildren and cameras would be caught by somebody.
If you actually believe that nobody else would have seen this.....come on.
If the only people with cameras running were journalists then chances are that those pictures did not survive. Kerry's falls are never preserved in pictures for posterity. That does not mean that the event occurred, just that there is little likelihood that there will be pictures available if it did happen.