[Mikendebbie]

Of course - that video is for the bedroom slide - which has a much smaller span compared to the living room slides - and I am not sure if the big living room slides are any different. They might actually have an aluminum frame/joists. Maybe someone here will know.

Edit: I found some sketches I did in the past that might illustrate the difference in the slides. I can't promise these sketches are 100% accurate, but probably better than nothing to help get you started.