YouTube has proudly announced that it is now capable of handling 4K video, despite the fact that nobody can actually watch it in all its glory.
In fact, you would need a refrigerator-sized projector to handle the full 4096x2304 resolution and considering the state of the real estate market you would probably have to sell your house to get one. For example, Sony's VPL-FH300L, which is merely a 2K projector costs €16,000, or as much as a mid-range car. Producing 4K video is a bit cheaper, as you can get a Red One camera for just $17,500, without the lens, of course.
Pointless as 4K support may be to the great unwashed, we have to take our hats off to the YouTube team. The sheer amount of CPU/storage resources and the bandwidth needed to pull this off is nothing short of breathtaking.