I heard about the first plane hitting one of the WTC towers on CBC Radio while I was getting my breakfast--I was eating a bowl of Cheerios, actually, with a banana diced up in it--and preparing to go to work, and I thought "Gawd, what a dreadful accident." A little while later I heard about the second one and thought "Twice is not an accident" and went to the living room and flipped on the tv. It soon became apparent that it was a deliberate assault, and I remember thinking something like "Somebody's going to get thumped for this, nobody does this to the USA and gets away with it. This means war, somewhere, in some form, soon." And my next thought was of my son, who was 19 at the time, the same age as a lot of the Canadian kids who died at Vimy Ridge and Ypres and Paaschendaele and on the beaches of Normandy and in Sicily and Italy and the Netherlands... and I was afraid for him.
I was several hours late for work that day. So were a lot of other people, for the same reason. I watched the images on the tv in horrified, stunned fascination. When I finally got to work, everybody seemed in about the same mental state I was in. Not much work got done that day.
I do not, however, think the world changed on that day. There's nothing particularly unique about terrorism or acts of war. All that happened was that some of the worst behaviour humans are capable of impacted a little closer to home than usual.
And I'll never watch that movie either. I ow what happened, I saw and heard about most of it almost in real time and saw multiple replays afterwards. I have no interest in seeing an agonizing dramatization of it.