I worked in cinemas during that era. Yes, I recall the 'split seats' technique, smoking on the left. but oddly enough in the 60's and 70's you didn't really get many complaints about it.
And back in the 60's when it was smoking everywhere, you could barely see the film through the hazo of smoke sometimes...but yet it seemed quite normal at the time.
Then in the mid to late 80's the whole health thing about cigarettes kicked off, and the complaints started to rise, so the cinema companies just decided to go with the flow and stop it. There was some resistance, of course, I remember back then it was not actualy against the law to smoke in cinemas and public places, it was only the rule of the premises. You could not actually stop someone smoking, but of course you could reserve the right to remove them from the premises,
However...one trailer that did take me by surprise on that video was the British Film Year one.
I doubt anyone on the planet remembers that one!
I think it was 1985, and it was an attempt to promote British movies. There were various special screenings of new British films, and there was a commitee made up of various industry people, including some cinema managers...of which I was one! I recall we used to meet in a room above what was then the Leicester Square Theatre (now the Odeon West End...I think).
The only screening I can remember is one we did for a movie called She'll Be Wearing Pink Pyjamas, with Julie Walters. It was about a group of middle aged women bonding on an outward bound course in the Lake District. I recall we showed it on a Sunday morning, and we tied lots of pink balloons to the bannisters.
Damned if I can remember anything else about the venture, as I recall I don't think it was particularly successful.