The theft was discovered on Sunday, when the church's baptistery was being prepared for a baptism, said Father Tom Elewaut, pastor at the church.
He said the video shows the suspect taking the relics from the locked baptistery, then putting the locks back on the gate and hiding from some visitors.
A man in Ventura County Jail on other charges has admitted taking the items, police said. But none have been recovered.
The suspect, who has not yet been identified by police, "probably didn't know what he was dealing with," said Father Elewaut. "They don't have much of a street value."
The relics measure about 2 to 3 inches.They are known as first-class saint relics, which means they contain a chip of the bone of the saint, Elewaut said.
There are two each of St. Bonaventure, St. Catherine Laboure and the mission's founder, Junipero Serra; and one each of St. Bernard, St. Vincent de Paul and St. Judas Tadeo, Elewaut said.
Seven of the relics were given to the mission by Vatican-sanctioned agencies, Elewaut said, and the others came from California.
Authorities hope someone will come forward with information leading to the relics.