There is no way to guarantee that video hasn't been manipulated or CGI generated. The most convincing video I ever saw actually had nothing to do with video. It was filmed in close enough that there should have been doppler shift in the audio of the jet engines coming in at full power. But there was no jet engine sound. The naysayers said the engines were clearly throttled back. But that contradicts the narrative of a hijacker trying to do as much damage as possible. At least at the last minute when the building is clearly locked in the flight path he will throttle up to full power. So I am dubious of the veracity of most of these videos. You can manipulate an audio track as well of course. It's just that most people don't think to do it or listen for it.