In the video on the Stretchsit cushion page, it seems that there is some sort of counterweight holding the cushion at the top of the folding chair. It turns out that I have exactly the same chair at home, and can't get the cushion to just stay at the top. I know Esther has said that you can just wedge the cushion behind, but I find that its difficult to get a stretch without it being anchored like it is in the car. Is there in fact a counterweight in this video? Are there any reccomended techniques for attaching the stretchsit cushion to such a folding chair or an office chair?