Nice build! You did a really nice job laying and folding that liner to get a beautiful smooth finished interior. I recently added that type of liner to an 8-foot tank of mine that had its epoxy inner sealing surface damaged while the tank was empty. I probably could have more easily just repaired the damaged spot with more epoxy, but I had a piece of black liner material just big enough to reline the whole tank and I went that route. The epoxy in that tank was blue, and I have regretted that colour choice since about two days after I filled the tank a few years ago. I took this opportunity to switch to my favourite interior colour...black...and couldn't be happier. But...despite using individual panels of liner material glued together at the seams to make a waterproof whole...I did the crappiest job in the world; wrinkles, folds, you name it. Yours looks terrific. Wonderful setup with the camera as well.
One comment/suggestion: The ends of the top cross-braces look to be fastened down with screws or lag bolts that go right through the liner wrapping the brace as well as the top edge of the pond liner. I've come to believe that every individual molecule of water in an aquarium spends its entire existence trying to get into places where you don't want it to be; much like all the water molecules on your roof, or in the soil around your home's foundation. It if were me, I would be tempted to run a nice bead of sealant all the way around the joint between the brace and the top of the wall, to prevent water creeping in and eventually reaching the wood around the screw holes and rotting it out.
I certainly hope you are kidding when you say that this is the final update!