Hijackers on the CCTV?

[spoon]

I read somewere that the CCTV footage showing Mohamed Atta is actually for a different airport not the final airport for boarding the planes, I cannot quite remember the proper details so can someone tell me if there has been footage shown of all the "19" hijackers in the airports as there must be CCTV footage of all of them?

If there is no footage then this is strange as we have seen lots of footage of the 7/7 and 21/7 bombers and again there must be footage of them in the airports prior to boarding. Why would this not be shown?

Thanks