Here's a clip from the summer of 1975 showing Synanon members getting married en masse. Synanon was a cult-like, quasi-religous group founded by Chuck Dederich. The group began as a way to help cure people of their drug habits, but became much more. 

In the clip, the couples wear period costumes. Many people are bald. A man with a large staff and pointy hat -- he's dressed like a Catholic bishop -- seems to be the officiant of the ceremony. 

A number of events appear to be complementing the mass wedding. The events include: 

• Skinny youth, dressed in white, prancing around while throwing about red and white flower petals;
• People wearing blue jean overalls, marching in formation while carrying banners with bird-like imagery; and
• A bald group of people wearing jogger-like attire and headbands, dancing back & forth, to & fro, and up & down in a hyperactive way.  

People on the sidelines, some of whom are in bleachers, watch the events unfold.