http://www.trueactivist.com/some-guy-has-pointed-out-something-really-strange-about-the-911-footage-weve-been-watching-all-these-years/
Hope that link works. If otherwise, he observes that much is wrong with the classic 9/11 plane footage - in particular a sort of CGI effect.
Doesn't look like CGI, it looks more like the result of a not so good conversion of video formats.