Why did it go viral? Well, as with most viral videos, the reasons are pretty simple: it's cool, inspiring, and has a great backstory.
From The Daily Dot:
Cirque du Soleil performer Dergin Tokmak lost most of the control of his legs as a child after contracting polio. But that never stopped his passion for dancing.
Sometimes, life can seem pretty bleak - especially when you are sat in front of your computer all day. Then something like this pops into your inbox, and you immediately feel uplifted. This guy didn't let his disability get in the way of being a fucking fantastic dancer. And that's a great story.
Hats off to you Dergin - keep on dancing.