Talbot is fighting 10 counts of indecent assault in cases dating from the 1960s to the 1980s, when he taught biology at Altrincham Grammar School for Boys in Greater Manchester, England.
Brown, 51, was a pupil at the school but is not one of the five men who have come forward with allegations against the weatherman.
The singer appeared at Manchester Minshull Street Crown Court as a witness for the prosecution on Tuesday and detailed Talbot's alleged behaviour when he taught at the school.
Brown stated in court that his former teacher made students watch an adult film during a lesson and asked students if they masturbated before suggesting they "go home and try it".
Talbot denies all 10 counts of indecent assault.
The trial continues.