It shall be a defense to a prosecution under section 28-813 that:
(1) Such person's activity consists of teaching in regularly established and recognized educational institutions, galleries or libraries, or the publication or use of standard textbooks, films, tapes or visual aids of any such institution, or the practice of licensed practitioners of medicine or of pharmacy in their regular business or profession, or the possession by established schools teaching art, or by public art galleries, or artists or models in the necessary line of their art, or to relevant references to, or accounts or portrayal of, nudity, sex, or excretion in religion, art, literature, history, science, medicine, public health, law, the judicial process, law enforcement, education, public libraries, or news reports and news pictures by any form of news media of general circulation;
(2) Such person has no financial interest in an activity, product, or event entitling such person to participate in the promotion, management, proceeds, or profits of the activity, product, or event, and such person's only connection with the activity, product, or event entitles such person to a reasonable salary or wages for services actually rendered; and
(3) The provisions of sections 28-807 to 28-829 with respect to the exhibition or the possession with the intent to exhibit of any obscene film shall not apply to a motion picture projectionist, usher, or ticket taker acting within the scope of his employment if such projectionist, usher, or ticket taker has no financial interest in the place wherein he is so employed. Such person shall be required to give testimony regarding such employment in all judicial proceedings brought under sections 28-807 to 28-829 when granted immunity by the trial judge.