I am not sure about the video you refer to. I don't understand the question about the "width of the rebar(b)" though. Rebar, at least the way I used it on my two greenhouses, was used only to anchor the structure, and had nothing to do with the height of the structures. Please expand on your question.
Also, please take a moment to go to your "Profile" and update your public profile, giving us your location. This can be city/state (best) or just your USDA zone.
By the way, welcome to ATP,
@terrible.