The man who was allegedly sworn at and threatened by an Ottawa bus driver apologized for his own behaviour Monday, but said the driver took his actions "too far" during the verbal altercation that was caught on video.

Matthew Taronno, who has a mild form of autism, said that as he rode the bus he recited a script he had written that contained some inappropriate language. He approached the driver to apologize for his behaviour, Taronno said, and that's when the driver got upset.

"He had a right to say what I did was wrong," Taronno told CTV Ottawa. "But he took it too far."

The incident, which took place last week, was shot by another passenger on the bus, who posted the clip to YouTube on Thursday.

In the minute-long, obscenity-laced video, a man believed to be the bus's driver repeatedly yells threats and swears and tells a passenger standing behind him to "shut up." The driver cannot be seen on the video.

"Don't say another f--king word," a voice can be heard yelling. "If you don't shut your f--king face I'm going to stick my fist in it."

Seconds later, the voice instructs the young man to exit the bus "when I open that f--king door" or face the prospect of getting beat up.

The passenger who posted the video said the incident took place on OC Transpo Bus 6671, en route from downtown Ottawa to Kanata.

In an interview with CTV Ottawa on Sunday, he said he pulled out his phone to tape the "bizarre" incident because he feared what might happen.

"I honestly thought a crime was going to be committed, so I just thought I would pull out my phone and videotape this," said the passenger, who wished to remain anonymous.

In his post to YouTube, the man said Taronno had been sitting on the bus and speaking as if he were "the host on a game show," before he got up to speak to the driver.

"After trying to apologize and state many times, ‘I'm sorry, I have a mental illness' the young man was subjected to verbal abuse from the bus driver," the video's description reads.

Taronno said the incident "made me feel uneasy" and his only intention in approaching the driver was to apologize.

"I didn't intend for it to be the way it was," he said. "I just wanted to apologize I guess for my actions that might have been offensive."

Alain Mercier, general manager of OC Transpo, issued a written apology for the incident while the agency investigates the matter.

Ottawa Mayor Jim Watson said he expects to hear back from OC Transpo about its investigation by the end of the week.

On Monday, Watson called the incident "not acceptable."

"I can't think of anything that would provoke that kind of vulgar and foul language being used in a public venue like a bus," he told CTV Ottawa.

The incident could be a public relations blow to the Ottawa bus driver's union, ATU 279, which has been mired in a labour dispute.

On Sunday, ATU 279 vice president Mike Aldrich said the union "does not condone" the behaviour demonstrated in the video, but said he wanted to know more about the circumstances that preceded the incident.

Taronno said sometimes he doesn't think before he acts, and said he was sorry for disturbing the peace on the bus.

"Sometimes I don't think before I act, and that was wrong and I apologize for that," he said. "I'll try and think for the future, and think before I act."

With a report from CTV Ottawa's Vanessa Lee