Uh, I don't think that's the case. At least one of these outfits, Cleanflicks, has a chain of video rental stores. I seriously doubt that they're buying individual copies of each video, cutting out the offensive stuff, then selling or renting that individual copy. Plus they're also selling DVDs, which by their nature means they're making copies.
If they bought one copy and then sold or rented multiple copies it would be a slam dunk case of copyright infringement and they would have been imediately shut down.
My case in point is "The Christmas Story". Some stations produce a version where a couple of curses are edited out, and another where "smarta$$", is changed to "smarty". I highly prefer that version, and I don't know why anyone should be concerned with that but me and my family. I cringe each time I see it with the curses, and it was a bad decision by the director to put that in there. It is, after all, a family film.