However it seems that if you do enjoy watching 4K videos on YouTube, here’s something to take into consideration. According to early reviews of the new Apple TV, it has been discovered that the device will not support 4K YouTube videos. While Apple has yet to officially comment on this, it has been speculated that this is due to Google using the VP9 codec, while the Apple TV supports H.264/HEVC.
As AppleInsider points out, the new chipset on the Apple TV does not support hardware encoding/decoding, but Apple could have gone the software route but for some reason did not choose to. The H.264/HEVC video format is more widely supported, but given how big of a platform YouTube is, it is surprising that Apple did not make an exception.
Maybe in the future Apple and Google will come to some kind of agreement for Apple to support the VP9 codec, but for now it looks like you’ll just have to enjoy your YouTube videos in Full HD.