Yes, they were films, shown on big screens via real/reel projectors. Some were in full size raked theaters and some were more like storefronts with theater seats on a level floor. The audience controlled themselves except for a few single men in the front rows making the floors sticky. These are the original "raincoaters". I don't know if they were gay or straight, but you did not see public sex in the theater during the movies.The big 70s movies attracted a lot of trendy couples and curious suburbanites. I saw Deep Throat, Misty Beethoven, and Behind the Green Door in very mixed crowds. Lots of what we now call yuppies in the seats.
Much, much later....after the porn theaters had died-out...you saw some couples doing public sex stuff in a few of the remaining theaters. There were several in the south that still had an active swinger scene as late as a few years ago. There are some yahoo groups and stuff about that.