Download 6K Red Dragon footage by Phil Holland, compressed to 4K at 15Mbit/s with Google VP9 codec.
To play the video you can use the latest VLC Player or Google Chrome.
The H.265 codec has a rival - YouTube are currently testing the next generation “H.265 beating” VP9 codec for high quality 4K streaming.
The file you see linked to above is nearly 2 minutes of 4K clocking in at under 200MB. The quality is astounding for 15Mbit/s and that in a nutshell is what the next generation codecs are all about. The new codecs have the potential to give us ProRes 4444 quality for 1% of the file sizes and make streaming of 4K video over current internet connections a reality.
The VP9 codec is developed by Google and already has the backing of Panasonic, Sigma, Sony, ARM and others. Interesting to note Sigma in that list!