As the people who uploaded the video point out, "This video captures a very rare herd of Pied/Calico whitetail deer were once common in Northern range. Due to over hunting in 1800's most were killed off. Recessive gene appears once every 20,000 births. Legal to hunt and regarded as a trophy due to its rarity, but it is wise woodsman-ship to allow to reproduce and increase numbers."
Less than 2% of whitetail deer are born piebald, though some think there used to be a higher percentage of them in parts of the US. They have frequently been the target of hunters in the 19th century, which may have culled their numbers.
The presence of white animals was and is often viewed as supernatural or sacred by many Native-American tribes - just this month, there was outrage over the killing of a spirit moose. We have to admit, if we saw a piebald deer in our sights, we'd have to think twice over whether we'd harvest it - sometimes you want to keep beauty around.