I didn't watch the entire video, but I have a few comments based on the part I did watch and my ownership of an OEM hard top.
I like the appearance of the eBay hard top. The OEM hard top looks odd from the side. The eBay hard top seems to enhance the looks of a Boxster.
My reservations about owning the eBay hard top are related to the build quality and materials. The OEM hard top is aluminum. The eBay hard top is fiberglass. I think aluminum is the superior material for this application. The OEM top has a glass rear window with a defroster. The eBay hardtop has a polycarbonate window with no defroster. I recommend that you research the long-term durability of polycarbonate before making a purchase. I found this video interesting.
It appears that with proper treatment, polycarbonate can be a good product on a vehicle, but you need to know exactly how the material is manufactured.
https://youtu.be/LmCmsYHNmbQ If you are comfortable with polycarbonate, you need to consider whether you can do without a defroster.
The OEM hard top fits well on the Boxster. You should be able to find some threads in which owners discuss fitment issues with the OEM hard top. The OEM hard top is adjustable, and I think most owners are able to resolve the problems they encounter with squeaks and rattles. The eBay hard top may fit fine and not have squeaks and rattles. But I would want to hear from people who actually owned one to confirm that. Designing and building a hard top that fits precisely on a Boxster is probably more difficult than it looks.
The OEM hard top has a headliner, and the interior fit and finish is consistent with the other materials in the car. The top in the video appears to be unfinished. I guess you could glue some headliner material to it, but I think it would be challenging to match the quality of the OEM top.
The OEM hard top has good weather stripping, and I don't think the peel and stick material on the eBay top will be as airtight as the OEM product. I would expect wind noise with the eBay top.
The mounting system for the eBay top seems to make it a more or less permanent installation. If you are happy with having it in place 100 percent of the time, that may not matter to you. I like being able to take my hard top on and off in about 15 minutes when the seasons change. I need a helper to avoid scratching the paint, but it is not a difficult job.
Overall, the eBay hard top looks great, but I think you need to explore whether there will be issues with fit, finish and wind noise before buying one.
Good luck.