It's taken years, but ultra high-definition (UHD, or 4K) video finally has a standardized physical media. Ultra HD Blu-ray is a new disc format that supports not only 4K, but high dynamic range (HDR) video and advanced surround sound formats as well. The Samsung UBD-K8500 is the first Ultra HD Blu-ray player we've tested, and it works very well. It's...