Buckley is facing three main charges of possessing objectionable publications, knowing they were objectionable, as well as three alternative charges of just possession that arise from four occasions over June 8, 12 and 19, 2018, when he saved the "Nunu" folder into his account.
Counsel Brendon Stephenson said the defence's case was that his client had no intention of seeking out that particular material, or of having or viewing it.
"At one point he did in fact open a video, realised within a few seconds that it was child sex abuse material, immediately [got] out of it, [got] himself off the Mega [app] and [did] not return," he said.
Buckley was searching the pornographic side of the internet during early June 2018, looking for particular videos.
On those "lawful" pornography sites, Buckley would read the comment sections to find other videos or links.
From there, he would sometimes end up on "blog-sites" that had content of a certain genre with endless pages of hyperlinks.
"I recall it mostly because it was frustrating to me," Buckley said about his Mega experience when he clicked on the hyperlink that took him to "Nunu".
He remembered the company asking him to download their application on his phone, and create an account before he could view any files.
Crown prosecutor Richard Smith asked Buckley why his recollection of events contradicted the evidence given earlier by Mega chief compliance officer Stephen Hall.
The link was available to anyone who had it and users did not have to have an account to view the material, Hall had said.
Buckley said he remembered Mega specifically because it asked him to perform tasks before viewing the material, whereas other links had not.
"I, in my heart of hearts, believe that I am not lying."
Once inside the Mega app, Buckley did not recall seeing thumbnails of videos or images as Hall and Department of Internal Affairs senior inspector John Peacock said the app would display.
"All I remember is seeing files, manila folders with names on them," he said.
He remembered clicking on the first one he saw until he got to a video, but upon seeing it was objectionable material, exited it immediately and deleted the folder.
He could not remember why there were three other times the folder was imported and deleted on his account.
However, Smith did not believe that after searching online for a specific area of pornography, Buckley randomly clicked on files through the "Nunu" folder without looking at what they were.
"It's not random because I'm on the sites looking for a particular kind of thing, and [the hyperlink] was on the site," the defendant replied.
Smith suggested Buckley was making up his story to fit with the evidence.
"No, I'm not."
When asked about why the name John Parker was used for Buckley's account, the defendant said it was the alias he had used for years in his hospitality work and Spider-Man was his favourite superhero.
"I didn't think I could be Spider-Man, but I could be his brother."
The trial continues.