Police at the trial played video footage that John Yettaw had filmed of himself inside the 63-year-old's lakeside home, where he spent two days earlier this month, said a spokesman for her National League for Democracy party.
Yettaw's bizarre intrusion led to Aung San Suu Kyi being charged with violating her house arrest, in a case that has provoked international outrage and calls for Myanmar's military regime to free her immediately.
"There was no other person except Yettaw himself in the video. He said that he had arrived at Aung San Suu Kyi's house," said NLD spokesman Nyan Win, who was inside the trial at the notorious Insein prison near Yangon.
The video showed the burly Yettaw standing in front of a picture of Aung San Suu Kyi's father, General Aung San, the country's independence hero, and speaking to the camera, Nyan Win said.
"He said he had asked her for permission to take photos, but she refused. She seemed scared, so he said he felt sorry because of that," he said, adding that the video lasted about two hours and was translated into Burmese.
Yettaw, 53, and two female political aides who live with Aung San Suu Kyi are also on trial.
Myanmar authorities had unexpectedly allowed diplomats and journalists to attend the trial for the first time on Wednesday, but abruptly announced on Thursday that the hearings would be back behind closed doors again.
A smiling, healthy-looking Aung San Suu Kyi had thanked diplomats for coming on Wednesday and said she hoped to meet them again in "better days." Footage of her was later shown on state television.
She later met envoys from Thailand, Singapore and Russia, expressing hope that "it was not too late for something good to come out of this unfortunate incident," a Singapore government statement said.
The regime has kept the Nobel Peace Prize winner in detention for 13 of the past 19 years. It filed the charges against her just weeks before a May 27 deadline when her latest six-year spell of detention expires.
Critics say the junta wants to keep her locked up ahead of elections planned for next year under a controversial "roadmap to democracy" that enshrines a role for the military in government.
The regime's opening up of the trial had appeared to be a small concession to mounting global anger, but in Washington, US Secretary of State Hillary Clinton said its treatment of Aung San Suu Kyi was "outrageous".
Clinton said the regime's treatment of Aung San Suu Kyi would automatically make the 2010 polls "illegitimate because of the way that they have treated her."
UN chief Ban Ki-moon meanwhile said he was "deeply concerned" about the situation in Myanmar and said he would bring up the issue with junta leader Senior General Than Shwe.
"I'm going to visit Myanmar as soon as possible. Now I am very serious in discussing with (the) government of Myanmar when I could be able to visit Myanmar," he told CNN.
Leading international jurists called for the UN Security Council to follow the precedent of Rwanda and the former Yugoslavia and hold an inquiry in Myanmar, saying the regime could be guilty of crimes against humanity.
"With Burma, there has been no such action from the UN Security Council despite being similarly aware of the widespread and systematic nature of the violations," said the report published by Harvard Law School, using Myanmar's former name.
The regime refused to recognise a landslide victory by the NLD in the last elections to be held in Myanmar in 1990. The military has ruled Myanmar since 1962.
