A few things, this post you linked https://www.sunlineclub.com/forums/f...ean-20295.html
is a 2006 or 2007 model year EPDM rubber roof that has wavy issues. It is a very different roof and issues then your 1993 metal roof but has similar service needs.
The metal roof of your video can have flex of the metal like that. The seamed metal roof is not fastened to the roof rafters directly. It just lays on top of the rafters, thus it can pop up and down like your video shows. The amount of flexing may change some between hot and cold temps.
You are wise to ask before getting on the roof. Your roof is not a direct walk on type of roof. The thin metal will not support your weight between the rafters without damaging the metal. You need to use smaller manageable sized pieces of plywood 3/8" thick or thicker to span over the rafters to spread your weight out. I used 3/8" thick 24 " or 30" wide by 48" long pieces of plywood. Large enough to spread the load out over 2 or more rafters, yet I can get it up on the roof.
See this setup, while this is for the Sunline rubber roof which is also not a direct walk on roof, it works the same for the metal roofs.
In this case, I am servicing the roof AC unit, but you use the same board setup for any roof item.
This starts with a very sturdy ladder on a solid footing. Getting on and off the ladder to the roof is a danger area. The ladder I saw in your video I would not recommend be used as it is not tall or stable at height enough.
Top protect the rubber surface from abrasion, I use tarps or other cloth, carpet, etc protection, then use the plywood sheets over the tarp. For the metal roof, using a protective tarp or sorts can help not scratch the metal. The plywood need is the same.
From your pictures, they are very good! You get an A+ on the pics.
This tank vent shows whatever sealant was used, did not bond to the plastic roof vent. It is lifted, may be a leak source and should be removed and cleaned before applying new caulking.
The same goes for the crank up roof vent, the caulking did not bond to the metal flange of the vent. Surprised if it is bonded well to the metal roof. This also should be removed and replaced.
To get off the old non stuck sealant, a dull scraper and a heat gun to warm it, not real hot, just warm it, can help the scrape up. And any left over small bits of small caulk, some caulk types will clean with mineral sprits and a rag rubbing it off. Then use a high flash cleaner like denatured alcohol or Naphtha etc. to get the left over mineral spirts residue off before applying the new Dicor caulk.
As to what to seal the roof with, this would be the roof metal seams and all roof flanges and gutter rails. I'm not sure what was used by the prior owner but they had a wrong choice on the tank vents and the crank up roof vents.
Some folks used Dyco 20/20, I have not used this as it is very thin, (6 mils thick) I have no info on how long it lasts, but it is cheaper then what I use. It may work well, but may also need to be applied more frequently.
This post is very common to yours here I suggest and Eternabond product on the seams, in place of using the Dyco 20/20. I come from a camper restoration background and any leak is a bad one. And I tend to use commercial roofing products in many cases, they have longer life warranties but also cost some more. https://www.sunlineclub.com/forums/f...tml#post157479
For the roof gutter rails, I suggest Dicor non sag roof sealant smoothed out, and Dicor self leveling sealant on the roof flanges. This is still RV world caulking, but it flexes with the camper and made for the vibration of towing and the metal, plastic and roof membranes campers use. This caulk needs to checked 4 times a year after the first year or so from applying. Any small hair line cracks need to be clean and resealed before they become larger.
The important need for any roof sealant, the area has to be clean. The sealants will not bond to dirt.
Also, caution on using silicone caulk on the roof or the the side of the camper. Normal home type silicone will not hold up long term, the bond to the metal will give way sooner or later from the flexing. The silicone itself will be intact, just not bonded to the camper.
Hope this helps