I assume it was Vio who posted this video in the plarail facebook group. Anyways, for those who don't have access to a facebook account, this set was made in 1972. Way earlier before i was born ha ha. Everytime the train passes through the trip arm, the advertisement switches. I guess you can make your own advertisements as long as you measure properly.
My Trackmaster/Tomy/Plarail Photo Gallery Page (over 600+ photos and still under construction)
https://www.flickr.com/photos/183311600@N03/
https://www.flickr.com/photos/183311600@N03/