They looked at the tape after firefighters called to tackle the early morning blaze at 53 South Street/88 North Street said they suspected it had been started deliberately.
Falkirk Sheriff Court heard last Thursday that after being tipped off officers viewed the camera images that showed Callum Scott at the scene.
Officers suspected he might have been involved and their inquiries later led to Scott being interviewed and then charged with wilfully setting fire to rubbish outside the premises that had started a blaze that caused between £50,000 and £75,000 worth of damage to the building and goods inside.
The court was told Scott had stood close by watching the building burn and at one stage had even been spoken to by one of the firefighters at the scene.
Sheriff Craig Caldwell jailed Scott, from 41-3 North Street, Bo’ness, for 18 months for the offence.
Defence lawyer Andy Bryson said the 25-year-old was “thankful” no-one had been injured in the blaze.
He told the court: “This appears to have happened when he was struggling with mental health issues and drinking a lot.
“He knows a non-custodial sentence is not an option here. He is now being treated for his mental health issues.”
The sheriff was told Scott, who was on bail at the time of the offence on April 9 last year, was appearing in court from custody because he is already serving a sentence for another matter and not due to be released until June.
He told him: “There is no alternative to custody here. This offence had the capacity to cause serious risk to life. As it was, it caused serious damage to the property.”
Sheriff Caldwell said that an “appropriate” sentence given Scott’s previous record was 20 months custody, but he was reducing that to 18 months due to the time of his guilty plea.
He also ordered that the sentence run consecutively with his current sentence.