Its a shame the 4k videos look like crap on youtube. I cant believe some people actually think they look impressive on the retina display.
A highly compressed 1hr 1080p MP4 (2.2GB) looks extremely impressive, where as this crap just looks pixellated to hell.
Unfortunately YouTube downgraded all their 4K videos to 2K. However they are still labeled as 4K.
Also resolution are you playing it at? I highly doubt that the high res videos are pixelated.