Something I remember from older forum topics of the subject is that "the vendors" rely on an affiliate program sales concept (or whatever it was). In essence
they themselves do not sell it, but a myriad of sales channels/affiliates sells it getting some little provision.
What many of the affiliates do is that they take lazy short cuts to skip work like testing the software at hand, gathering promotional screen shots and videos themselves (note that the affiliates rarely market only one software). Instead they copy stuff from other YouTube videos and screenshots from all over the place. Many flight simulator geeks can differentiate between FlightSimulator X, X-Plane and FlightGear video snippets and screenshots used in those videos.
At one time some years ago one of the videographers on this forum had probably flagged a hundred or so videos partially using snippets from his videos.