In the interview, Detective Laurie Howell asked Macdonald whether he had vandalised a new house being built on the Guys' property.
The Crown alleges he damaged the house, and earlier burned down an old house on the property, to intimidate Mr Guy's wife Kylee off the farm.
Mr Howell said he was ``pretty concerned'' by inconsistencies in Macdonald's statement and asked him bluntly: ``Did you go and do that damage to the house?''
Macdonald said he did not and denied any knowledge of the damage.
Mr Howell said police had formed the view that whoever committed the attacks was responsible for Mr Guy's murder.
``I guess it sort of makes sense,'' Macdonald replied.
Later in the interview, Mr Howell asked Macdonald if he thought his friend and workmate Callum Boe had told police the truth about the damage.
Macdonald replied he thought he had.
Mr Howell then asked him if he wanted to change his story based on what Boe - his younger accomplice - had told police.
``He was probably involved,'' Macdonald said.
Asked who with, Macdonald said: ``Me.''
Macdonald said Kylee had not done anything to him but agreed it was directed at the Guys.
``I don't know if it was about the new house ... It wasn't a fair partnership. Slogged my guts out, worked my ass off.''
Asked about his earlier comments that he had got over his disagreements with Mr Guy, he said: ``I still was holding a bit of a grudge.''
Mr Howell also asked him about the arson of the old house on the Guys' property.
Macdonald said he ``burnt it''.
Asked why, he said: ``I don't know. Yeah, just thought that it would be funny ... It wasn't directed at Scott and Kylee in vengeance.''
Mr Howell also asked Macdonald about his involvement in the theft of two deer from the nearby Hocken farm.
``We took two deer. I don't have to explain more than that.''
Mr Howell asked him why.
``I don't know, it was a challenge. I don't have a reason why, we just did it.''
Macdonald admitted he buried the deer on the farm by a rubbish hole on the same morning he and Boe took them.
He denied any knowledge of notes left in the Guys' letterbox.
Throughout the interview Macdonald - dressed in a green zip-up sweater - leaned against the table, crossed his arms or leaned back in his chair while talking to police.
The video screening continues.