The video was being studied as students and faculty members prepared to return to Sparks Middle School, where a boy fatally shot a teacher, wounded two classmates and killed himself on Monday.
The shooter was identified on Thursday as Jose Reyes by Sparks city spokesman Adam R. Mayberry.
Washoe County School District spokeswoman Victoria Campbell said school officials were examining the video but cannot comment because it's part of the broader investigation into the shooting just outside the school building about 5 miles northeast of downtown Reno.
Reno's KRNV-TV has reported that some students at the school said they watched the video, entitled "Bullying," earlier this month. The station has broadcast excerpts.
School district police chief Mike Mieras planned to address reporters later Thursday at the middle school, where students spent the day decorating the gymnasium with tributes to their beloved math teacher Michael Landsberry.
"But he cannot discuss the video because it is part of the investigation," Campbell told The Associated Press.
It wasn't clear if the video had been seen by the young gunman, who Sparks police previously refused to identify. Police had said they wanted to respect the boy's family but came under pressure from media organizations over that decision.
City officials previously acknowledged a report from the Univision affiliate in Reno that disclosed the name and said they would release it publicly to be fair to families and other media outlets.
School superintendent Pedro Martinez said in an extensive mass email to all district parents that school officials are reaching out to provide counseling and other services. Parents were encouraged to do the same.
"It is difficult to imagine something of this nature happening in our own community and impacting us so closely," Martinez said.
"We know we will be feeling many emotions as we struggle to understand and cope with this incident," he wrote.
Landsberry, 45, was an ex-Marine who coached basketball and soccer and was known by all as a big fan of Batman.
In his email, Martinez outlined a variety of resources available to families, including a crisis call center and the Northern Nevada Mental Health Services.
It was sent Wednesday night while hundreds of students and others gathered at a candlelight vigil outside the school, where community leaders and clergy offered prayers and words of encouragement.
"We pray for a world where guns and children don't go together where violence is not the first or second or third way children think of to solve problems," said Julia Rubin of Reno's Temple Sinai. "We pray after we have mourned and comforted each other we can take steps to address the root cause of violence and gun use by children throughout our country."
Spanish Springs Presbyterian Church Pastor Howard Dotson led students in a pledge to "be a peacemaker."
"There is nothing glorious or sexy about guns," they repeated after him. "I want to learn and grow old and have many children."
Meanwhile, the mother of one of the wounded boys told reporters she's committed to helping promote gun safety in the community, and her son said he used to think of guns as a toy, but not anymore.
Jenifer Davis said it's a "miracle" that her 12-year-old son, Mason Kamerer, survived the shooting.
"As a result of this incident, I will be getting involved with issues around gun safety in the hopes of preventing this kind of situation in the future," said Davis, who said she has owned guns and always kept them locked but will be even more proactive in the future.
Kamerer told CNN he heard what sounded like distant gunfire and spotted Landsberry lying motionless on the ground before he found himself within 10 to 20 feet of the shooter, who said nothing before firing a single shot.