By Margaret Sullivan / The Washington Post

The pounding on the Capitol doors, the shouts of the mob, police officers screaming in pain, barricades toppled, windows shattered, the deadly gunshot.

Captured in fragments on cellphone videos and security cameras during the Jan. 6 insurrection, these sounds and images are more than a month old now. Many of them had been uploaded and broadcast and retweeted millions of times before House impeachment managers presented them in a 13-minute video compilation Tuesday at the beginning of former president Donald Trump’s second impeachment trial.

By modern standards, the footage is ancient.

So you would think that its power would have waned by now. That the impact of those horrible sounds and images would have faded through sheer repetition.

Instead, every second seemed as terrifying as the day it was recorded. More so, in fact.

“This is still completely unbelievable and so traumatizing,” PBS White House correspondent Yamiche Alcindor tweeted as she watched it.

Vanity Fair writer Joe Hagan wrote,”This is making me ill.”

What is it about the Jan. 6 footage that defies the thermodynamic law of the internet age, that makes it grow more compelling with time?

I suspect it’s because not until Tuesday’s presentation — a simply produced, chronological sequence of stomach-churning sights and sounds — did anyone have a chance to process what the clips showed. Before the video, the footage had existed merely as a jumble of disaggregated clips, dumped onto social media after the attack, then looped endlessly on cable news and phone screens.

Now, we could finally see context. We could see cause and effect.

Here was President Trump at his rally near the White House, lighting the fuse for the riot with a lie-filled speech about election theft and taking back the country, promising to march with the mob to the Capitol.

Here was Vice President Mike Pence entering the Senate chamber a couple of miles away at almost the same time, nodding to the lawmakers preparing to certify the election results.

And here was the mob: pounding on doors, breaking through windows. Here was a police officer crushed in a doorway, blood pouring down his face. Here was another officer, Eugene Goodman, bravely making himself into a decoy to lure the rioters away from their targets. And now the gunfire: the moment where an officer shot one of Trump’s true believers, Ashli Babbitt, as she tried to vault through a barricaded window to enter the Speaker’s Lobby just yards away from the lawmakers.

And later — far too late — here was Trump finally telling his insurrectionists to go home, assuring them that he loved them, that they were “very special.” And still later in a tweet, urging them to “Remember this day forever!”

Set down in a straightforward timeline, the cellphone clips began to form something understandable, if not remotely sensible.

And part of what was understood was this: As bad as the attack was, it could easily have turned into a complete bloodbath.

Speaking afterward, Trump’s defense attorney David Schoen tried to buffer the video’s gut punch. He said it was too slick;a Hollywoodesque flick spliced and diced into something “to chill and horrify you.”

In fact, the video succeeded by doing the opposite. It reassembled shards and snippets into something whole.

Some Republican senators tried to avert their gaze. Rand Paul doodled on a pad of lined paper and Rick Scott tried to busy himself with paperwork, The Washington Post reported. Tom Cotton and Marco Rubio, too, turned away from the obvious, irrefutable truth on the screen: that Congress had been attacked by a mob inflamed by the president of the United States.

It’s not possible for the rest of us to look away, though. And every time we look, it only gets worse.

Margaret Sullivan is The Washington Post’s media columnist. Previously, she was the New York Times public editor, and the chief editor of the Buffalo News, her hometown paper.