Defense attorney A. Charles Peruto Jr. argued that Gibson only violated police rules. He said many officers do not turn in evidence or do required paperwork until a shift's end.
Assistant District Attorney Michael Kershaw, however, said that Gibson had no warrant to search the Lexus and that the cash he took was not in plain view.
The video shows Gibson's right hand rooting through the center console, sun visors, and glove compartment and taking two packets of cash.
Police officials said fellow officers had complained that Gibson lifted clothing and jewelry in searching suspects' homes.
FBI agent Thomas Duffy testified that he parked the Lexus at Ninth and Loudon Streets in Logan on Jan. 31 after planting cash, "prop drugs," and a gold Rolex watch inside.
Gibson was assigned to take possession of the Lexus from the officer who stopped the driver and return to the Narcotics Field Unit in Kensington.
Duffy testified that he and other agents watched Gibson pick up the car and followed him to the narcotics unit lot.
When Gibson went out on another assignment, Duffy said he checked the Lexus and discovered $100 he had planted in the center console and $40 in the pocket of a pair of sweatpants were missing.
Duffy said Gibson was picked up and told he was under investigation.
"Oh, you must mean the money," Gibson replied, according to Duffy, who said Gibson pulled the cash out of a pocket.
Duffy testified that the planted cash had been dusted with powder that glowed under ultraviolet light. Gibson's hands and the cash tested positive.
Duffy said that he asked if Gibson wanted to make a statement, but Gibson declined.
Gibson and Corbett's daughter, Katherine Corbett Gibson, a former city prosecutor, have been married since 2010 and have a 1-year-old son. They have reportedly separated.
Contact Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.