SAN DIEGO -- A local medical marijuana collective operator accused of being a drug dealer insists he has done nothing wrong as his trial began Thursday.

Surveillance video from a November 2008 undercover drug operation showed what prosecutors called an illegal drug deal between marijuana advocate Eugene Davidovich and an undercover detective.

Deputy District Attorney Theresa Pham said, "In order to be able to facilitate the investigation -- the operation -- it was necessary for him to take on an undercover alias."

In the footage, two men are seen standing on the porch outside a Pacific Beach home. The undercover officer posed as a medical marijuana user under the alias Jamie Conlen. Davidovich admitted he came to the home to sell marijuana.

Defense attorney Michael McCabe said, "He believed, legitimately, that Jamie Conlen was in fact a legitimate patient."

McCabe said Davidovich operates a medical marijuana collective, which allows medical marijuana patients to produce and sell marijuana to each other as long as they are not doing so for profit under Prop. 215.

McCabe said Davidovich made it clear in early phone conversations with his buyer that the purchase was part of the collective.

On Wednesday, the undercover officer told jurors he did not recall Davidovich mentioning the collective and insisted it appeared to simply be an illegal drug deal.

The surveillance footage showed Davidovich asking for the undercover officer's medical marijuana ID card outside the home, and then the actual transaction took place inside the home.

The officer said he never recorded the audio from the phone conversations he had with Davidovich. McCabe said it is evidence that would have proven his client was upfront and innocent.

The undercover drug operation was part of a program called Operation Endless Summer.

The goal of the operation was to wipe out drug trafficking within San Diego's military housing areas.