Sweet fancy Moses, YouTube can now display full-resolution video shot on 4K cameras from the likes of Red Digital Cinema. That kind of footage is a bit rare, as YouTube's demo playlist only contains four clips, and as the blog post suggests, "the ideal screen size for a 4K video is 25 feet."
The resolution is 4096x3072, which is "nearly four times the size of 1080p." YouTube also warns that you'll need an "ultra-fast high-speed" connection.
Practical? Not really, but cool nonetheless. If your connection is fast enough, check out some of the sample clips. They look pretty good even if your monitor is slightly smaller than 25 feet.
Twenty five feet
Who do you think I am