Hi, Burton W. Welcome to the PPI forums. It's good to have you here.
I tend to agree with you. My assumption is that most (if not all) of these are staged, and that the limitations of manpower and ingenuity always determine how these are choreographed. For the record, I've never seen poltergeist activity with my own eyes, and until I do, I'm wary of videos like this where poltergeist activity appears staged for our entertainment right in front of the camera. In particular, the staggered timing of them is dubious. Most of these extremely low-tech and strictly mechanical effects can't be undertaken simultaneously because one person can't be in two places at once or they've got their two hands full pulling objects on fishing line off camera in singular trajectories . They never do anything remarkable, like levitating a fish bowl or scratching a message in the glass. As corny as it is, watching a penny slide up the face of a solid wood door would have a lot more impact on me. But, in some ways, our imagination and our technical abilities to stage these haunted attractions for YouTube hasn't changed much since the 19th c and its carnival of seances.

Anyway, it'd be a pleasure to hear your further thoughts about this.