Mr Platt said he apologised to the boy later.
Mr Platt's wife said he wasn't at all like "that", but she had seen the footage and acknowledged it did look bad.
'Everyone hates a bully'
Meanwhile another man who witnessed the attack says he got involved because "everyone hates a bully".
Leighton Dyer said the boy who was wiped off his skateboard looked to be about 13-years-old and Mr Dyer, 38, estimated he would weigh about 45kg.
Mr Dyer did not plan to lay a complaint over being shoved, saying he just wanted the skate park back to normal.
He did not know if the boy's parents planned to lodge a police complaint but said he would if it was his child.
The competition took place yesterday afternoon and was aimed at children as young as 6-years-old.
Mr Dyer said he had been involved in skating both here and in Britain for more than 20 years.
Meanwhile police revealed that a member of the public, who attended the event with his family, said the sponsor's representatives were verbally abusing children at the park while telling them to vacate the ramps at or near the skate park.
Another man later called police to complain of being assaulted by a security guard at the event.
Organisers claim it was staged
This afternoon organiser of the skateboard competition says he believes the whole thing was staged.
William "Doc'' Murdoch is the programme director for Serenity Addiction Clinic - the organisation who ran the competition.
Mr Murdoch said Mr Dyer was among a group of skaters who appeared to want to sabotage the competition, which was aimed at children as young as 6 six years old.
Mr Murdoch said as the competition was taking place, a number of teenagers on skateboarders began intercepting youngsters taking part in the competition.
Mr Murdoch said Mr Platt was in no way associated with the clinic or involved with the security team.
"That person is a parent whose child was involved in the skate comp. We do not, nor do I condone violence of any form.''
Mr Murdoch questioned why Mr Dyer and others turned up to the park with a video camera as the competition was going.
"I think it's really unfortunate that you had a guy show up with a video camera, who on purpose brings some people to the park to disrupt the competition.
"Then he starts yelling at people and yelling at kids. Then he wants to get in the face of a parent whose going to protect his kid - and then there's a debacle.
"It was all staged - we all know that. We all saw the whole thing.''
However, Mr Dyer says he was only trying to help.
"We just want our skate park clean. We don't need bullies down there. That's the only thing we want - we just want it to be clean...and with no thugs.
"All the older skateboarders try to hang out with the kids and make sure that one, they don't do stupid stuff and two, don't get in trouble.''
Tagging, graffiti
In addition to the altercation, there are claims youngsters in the competition were also given spray cans by organisers to tag the popular skate park.
Victoria Park Skate Park was left littered with tags with the names of sponsors including well-known brands such as Cheapskates, Wild Poppies and Dick Smith.
The vandalism and video footage prompted a swift response from Auckland Mayor Len Brown this morning.
Len Brown tweeted this morning: "Very unimpressed by vandalism at Vic Park skate park & appalled by accusations of comp organisers handing out spray cans. Am investigating.''
He later posted on Facebook: "I am shocked and appalled by the antics at Vic Park Skatepark over the weekend.
"Vandalism is bad enough, but shoving kids around is quite another matter. I'm taking this very seriously. This must be a safe place for our kids."
