I had a keg for several years and I can tell by your video that there is a LOT to like about your new cooker. They took a lot of the ideas that In-zone had with the keg and expanded on them even further. I'm afraid that you will eventually have to seal off that lower gasket. It's a great concept but I just can't see it going the long haul. I hope it does though. If it that happens, just take a pie pan and use it to pull the ash out the top. It's nice that the flanges are their for the diffuser to sit on because that would make great "handles" for pulling the fire box out. BK doesn't have that so it can be a little awkward to pull out.
I think you are going to be really happy with that cooker.