Gotcha! I did think you were talking about 'em promo videos, but you also mentioned about not wanting to watch shorter videos in general.
I do dislike those promo vids, and would only save or bookmark them to try finding the full video later. I wouldn't know why others would collect them other than for that reason, but yeah… maybe they just really like the guys they see, or are new to collecting porn so most anything would be hot to them -- I dunno.
But I think I'm getting what you're saying, even how you are. Correct me if I'm wrong, but you like getting into the film/video (i.e. the actors/models, the story/scene, etc.) at a certain pace, and it takes time for you to build that momentum to like what's going on and would like or prefer to keep it going for a while. I'm the same way sometimes (and sometimes, I just wanna get off quick haha).