The Post's Rosalind S. Helderman obtained a video featuring White House senior policy adviser Stephen Miller when he was in high school. Here's what she learned from it. (Bastien Inzaurralde/The Washington Post)

Long before President Trump's 31-year-old aide Stephen Miller was shaping policy in the White House and making questionable allegations about voter fraud, he was booed off the stage as a student during a speech to his classmates at Santa Monica High School.

That moment was recalled on Twitter in recent days by Milwaukee Brewers baseball player Cody Decker, who attended the same liberal California high school as Miller -- and it was captured in a video obtained this week by The Washington Post.

Decker tweeted about the high school memory after a decidedly mixed debut on the Sunday show circuit for Miller, who served as Trump's speech writer during the presidential campaign and was a chief architect of the executive order barring travel from seven Muslim-majority nations. At one point Sunday, Miller declared that the president's national security decisions "will not be questioned." He also claimed, without evidence, that thousands of Massachusetts residents illegally cast ballots in New Hampshire in the presidential election.

On MSNBC, Joe Scarborough declared Miller had been "horrendous" and "embarrassing," though Trump tweeted that he thought Miller had done a "great job."

As explained in a recent Washington Post profile of Miller, the Trump aide has been a conservative provocateur since his days at Santa Monica High School, where he defined himself in opposition to the overwhelmingly liberal community. He appeared on a nationally syndicated conservative talk show 70 times before his high school graduation to decry political correctness and multiculturalism.

[Stephen Miller: A key engineer for Trump’s ‘America first’ agenda]

Miller was a controversial enough figure at his school that his classmates put together a short documentary about him. That's the video that was provided to The Post. Included in the video, which was first published by Univision, are a few clips of Miller speaking at the school's outdoor Greek theater as part of his campaign for a student government position. "Hi. I'm Stephen Miller," he begins, as classmates can be heard hissing. "Some of you may--or may not--know who I am."

"I will say and I will do things, that no one else in their right mind would do," he says later in the speech.

Still later, Miller announced to the crowd, his voice rising, "Am I the only one who is sick and tired of being told to pick up my trash when we have plenty of janitors who are paid to do it for us?!"

Eventually, Miller can be seen on the video laughing as he is pushed off the stage, as his classmates continued to boo.

Most of the video given to the Post features some of Miller’s classmates dissecting his tactics. One said she believed he expressed his views in an insulting manner. Another said she thought Miller "adds flavor" to their liberal school.

A friend of Miller's, Chris Moritz, is captured on the video saying that the janitor line was a joke. Moritz, 31, now an investment banker, reiterated that recollection in an email to The Post, saying Miller’s speech had been “delivered as satire, a [Stephen] Colbert style routine that was a deviation from his political activities.”

“I think everyone at the time, especially those who knew Stephen, understood that this was a senior prank,” Moritz added.

The video includes only a few clips from Miller's speech. A spokeswoman for the school district said officials have been unable to locate a full video of the speech.

Miller declined to comment. A White House official emailed a statement calling it “pathetic” that The Post “thinks a fifteen-year-old teenage high school video is newsworthy.”

In an interview, Decker recalled that Miller's speech was short and punctuated by jeers throughout. "Literally, it took 15 seconds of what he was saying for the boos to really start," he said.

"I just remember that it started and it was exceedingly contentious," Decker recalled. "Then it turned to volatile, about as fast as you could be imagine. Then it turned out that he had to be removed from the stage because he wouldn't leave. It was cringe-worthy."