The chips were previously available, e.g. from Individual Computers, which also produced new, improved mainboards (the C64 Reloaded) and a lot of other hardware and accessories for the C64 (and also for the Amiga computers).
The case is from a previous kickstarter campaign, which you can also buy normally now.
New are the keycaps itself, which finally seem to be shipping from the crowd funding campaign. Most likely he also backed the first attempt from someone who found and bought the original molding machine for the keycaps, but got bogged down by small little details and sadly never delivered. So it's good to see, that the second crowdfunding campaign from a different person who recreated the keys in a 3D layout and then went on to let them cut/print elsewhere, but which also took a long time to finally happen. Not few - including me - thought they lost their money a second time.
Since there existed previous test samples from both key campaigns, I'm confident someone already built a completely new C64 this century.
So, there you have it. The original video headline is quite a bit clickbaity and I honestly expected he did the layout of a completely new C64 board; nevertheless the video is fun and I'm happy that the C64 (scene) lives on in so many hearts.