Rachel Fee, 31, and her partner Nyomi Fee, 28, are accused of murdering the two-year-old in March 2014 at a house near Glenrothes, Fife, and ill-treating two other boys.
The two women deny all the charges against them.
Jurors immediately asked for a break after watching the 12-minute film.
The video was shown to the jury at the High Court in Livingston.
It showed Liam lying on the floor of his bedroom in his pyjamas, covered in a duvet. The video was taken by detectives in the early hours of 23 March 2014.
The court had previously heard paramedics arrived at the house just after 20:00 the previous evening.
The video showed each room of the house where the toddler lived with Rachel and Nyomi Fee. There was a cot in the room, alongside a buggy and pictures of Liam on the wall.
Later, Police Constable Sam Girdwood, 24, told the trial he and his partner were called to the house after receiving a report a baby was in cardiac arrest and may have been strangled by a young boy.
Pc Girdwood said he arrived and Rachel Fee was standing with the boy who she and Nyomi are accused of falsely blaming for Liam's death.
He said: "She had a hold of the young boy and told him to tell me what had happened. He mumbled something that sounded like 'I strangled him'."
The officer said he took the boy into a separate room from the women where he repeated the claim, and brought it up later at Glenrothes police station.
He said: "He wanted to tell me what happened. He put his hand up in the air to say he had done this to (Liam). He went on to say something along the lines of (Liam) was getting more attention than him."
Both accused, who are originally from Ryton, Tyne and Wear, also wept as the video was played to the jury.
The couple are accused of murdering Liam and attempting to defeat the ends of justice by blaming the killing on a young boy.
They are also charged with a catalogue of allegations that they neglected Liam and abused two other children, one of whom they blame for killing Liam, while in their care over a two-year period.
They deny all the charges against them.
The trial continues.
Members of the jury in the Liam Fee murder trial wept as they were shown a police video of the toddler's body hours after he was found dead.