I'm pretty sure this isn't new footage; I remember seeing these very scenes at the time, especially the angled-up shot of the 2nd plane at 3:00. This is not new. Still feels like time-travel though.
I remember the part at 3:00 making its rounds on all the big networks a day or two after it happened.
The most memorable "raw footage" video of 9/11 to me is the one shot by Jim Huibregtse. He started recording just a few seconds after the first plane hit and most of the video after that is almost interrupted and shot from the same angle. It's surreal to see trails of smoke gradually appearing from the sides of the tower as people inside begin to smash out the windows to get air.