I was on a PC at school when the first news report came in over the internet that a plane stuck one of the towers. The news article I read made it sound like it was hit by a small plane, and not a passenger airline.

Then, nothing. Our internet went down. It turns out Comcast relied on the fiber under WTC 1&2 for a large part of their east coast backbone.

We found out that the first tower collapsed by (no kidding) standing outside of one of our teacher's cars and listening to his car radio.

A few years before 9/11 a Cessna had crashed into the Empire State Building in the fog and when someone in class said a plane had crashed into the World Trade Center I assumed it was a similar thing.

I know I didn't see it live but it would've been easy to fool myself into thinking I did. The news services would run unedited footage of the plane crashes and buildings burning virtually all day. And they don't do that anymore. So your brain has this image of continuous footage but can't correlate it to modern journalistic practices of how this event is portrayed in tge media. So you think "Oh, I must have seen it live."