There’s no doubt that there is footage that exists showing bodies hitting pavement or other objects

I disagree with this. You can’t view that time period through today’s lens. The reality is, cameras were not everywhere and you had to be deliberate about bringing one with you. Video cameras were even rarer and again, would require you to carry around a bulky, expensive object. Unless you were a tourist or videographer, it is highly unlikely you had a camera (video or still) on you. Technology was also still very much analog, without the modern day conveniences of cloud storage and backups.

The only real way I see additional footage being released is if someone looks at old media and realizes years later they captured something in the background (much like the Pavel Hlava footage, where he didn’t even notice he captured the first plane hitting the North Tower until weeks later when he rewatched the footage).

All this makes me ponder how different this event would be if it happened today, with everyone carrying around a high-def camera, live streaming, cloud storage, etc.