I think that by "beaded steps" he means covered with vinyl liner, and held in place by a bead (tab) on the back side of each step (I think in the corner where each tread meets the next riser going up), which fits into a bead receiver incorporated into the step support system behind it.
I can't seem to find much info/pictures on the internet thoroughly describing these two methods on steps either. If anyone on here has some it would be great to see them!
Are you recommending the plastic steps with gasket? I've seen some people vinyl over them when they eventually crack or leak, and assumed these were less desirable; but I don't know for sure...
edit: just found this on the beaded step:
http://www.youtube.com/user/tkennedy74# ... J0Z7qaiKj0