Chams suffered greatly under the Khmer Rouge, and their plight in part makes up the charges of genocide against the four leaders.
The observer dismisses the transferring of cases to local courts as a plausible solution to the court's financial problems.
As many as 200,000 people were forced into marriage under the Khmer Rouge, which sought a communist agrarian utopia.
Duch was arrested in May 1999 and was later charged by the tribunal for war crimes, crimes against humanity, torture and homicide.
A leading Khmer Rouge tribunal monitor said Monday he was optimistic about the UN-backed court.
The 93-minute film has won 16 awards in the US and other foreign countries, including the Special Jury Prize at Sundance.
Nuon Chea, 84, is charged with war crimes, crimes against humanity and genocide, for his role in the Khmer Rouge.
Meanwhile, the tribunal continues to face funding woes, as donors wait for a completion strategy before deciding on the amount of funds.
As many as 200,000 people were forced into marriage during the Khmer Rouge rule between 1975 and 1979, according to research.
Tribunal spokesman Lars Olsen said Wednesday that rape and forced marriage are included in the indictments for Case 002.