These are trailers throughout the decades. They are also called previews. The enoying videos in front of the feature you are waiting to come on in the theater. They are collected here on this site.
This are an art form in and of themselves, sometimes giving up too much of the movie itself, some will say. They measure in length between 30 seconds or so to over 6 minutes. And some can become really risque. From various countries. I tried to have the subtitles of the foreign movies when available. Some previews are restored and will say so in the preview.
These are all theatrical previews but recently, and they will advertise, will be on streaming services such as Netflix, Amazon or Apple+ soon after. Some previews, nowadays, will say coming to theaters only. This is the way it is for now.