Those are some *very* obvious seams. It's kinda sad that Sonic games from 30 years ago did such things better.
That's because they were 2D made, before 3D got into the industry. I've seen those seams in that video, and those aren't what we see in 2D games at all. Wrapping levels in whatever direction or 2D axis, X or Y, are seamless for that to work. Trying to do that in 3D makes it awkward to see.