The film chronicles the golden age of Cambodian rock, before the country fell to the Khmer Rouge, which killed many musicians.
Hearings Thursday included testimony from a witness at the Kraing Tachann security center, where an estimated 15,000 died.
The holiday is particularly contentious, because it also marks the beginning of a decade-long occupation by Vietnamese forces.
“Hope for the Future,” a new film by the Documentation Center of Cambodia, tells the story of Sek Say, a young girl who lost both parents to the Khmer Rouge.
A tribunal spokesman said the Supreme Court will determine whether Thet Sambath will testify or not, based on the law.
Chhang Youk, director of the Sleuk Rith Institute, said he named his research institute after the material in an effort to promote better understanding of Cambodia’s identity, culture and history.
Sum Rithy was accused of spying for the Central Intelligence Agency—a common charge among Khmer Rouge—in the 1970s and imprisoned in Siem Reap.
The Khmer Rouge tribunal has ordered the appointments of two defense attorneys to represent jailed leader Khieu Samphan and break through an ongoing boycott of proceedings.
Khieu Samphan has refused to participate in the second phase of an atrocity crimes trial against him and fellow leader Nuon Chea.
The tribunal’s international investigating judge is examining more than 10 crime sites for Case 003 and some 55 crime scenarios for Case 004.
Defense lawyer Kong Sam Onn told VOA Khmer his client had met with court officials from the Defense Support Section and told them “that his stance is not changed.”
The second and final phase of the trial against Khieu Samphan and Nuon Chea are widely viewed as the court’s most important case.