A painted piano near Curtis Street on the 16th Street Mall is missing more than one key. It’s not in tune. It sits outside in the elements all day, as buses whiz by in both directions amid the busy downtown Denver streets.

But one 20-year-old who has never even taken a lesson can still attract a crowd at this very piano – as two million people who have seen a Facebook video posted by a man who didn’t even know him can attest.

Deon Fisher wasn’t quite aware the video had been seen that many times since it was posted on Dec. 10. In fact, it didn’t even seem to concern him too much.

FACEBOOK VIDEO: Deon Fisher shows incredible piano skills

“I just like playing for people,” he said. “I just like that they appreciate me coming. As long as they like it, you’re good.”

Fisher has been playing piano for four and a half years. It started when he was watching his friend play the theme song from Harry Potter in his basement.

That’s when Fisher says he started to learn “Secrets” – a song he’d wanted to play for a while -- two fingers at a time. Slowly, he became more comfortable, experimenting with different chord progressions and grooves, creating his own compositions with simply what he says he’s feeling at the time.

“When I touch the first key, or depending on the music I was listening to before, it creates just a tempo in my head or a groove in my body that makes me just like want to do whatever,” he said. “Like anything, and it just comes down, I have no idea.

“… it’s like reading a book,” Fisher said. “You’re following with your finger, but really with a piano, you have no idea what’s going to happen. As long as you stay in the range of the keys that you know, you could press anything, groove any way you want to, and it will sound nice.”

Fisher says he worked three jobs when he was just 16, waking up at 5:30 a.m. to take a bus from Southlands to Golden, then to Westminster, and then back home.

Now, he teaches kids how to tumble on trampolines and has a hummus company with a pair of friends.

In his free time, he says he breakdances – and of course plays piano wherever he can, be it on the 16th Street Mall, cafes in Boulder or even Guitar Center.

He doesn’t have his own keyboard.

Fisher says he’ll play outside regardless of the weather. Sometimes when it’s super cold, he says his fingers have a hard time playing fast. One time, he was so amped up he got cysts on his hand that prevented him from playing for a little while.

For him, playing piano is in a lot of ways a release.

“When you take all of the stuff in and you analyze everything, I come down here, I just express whatever was going on here, it’s still there, then by the end I’m refreshed, and I just shared with anyone who was listening what was going on,” he said. “They had no idea what was going on, but they are emotionally connected if they took the time to sit here and listen.”

WATCH: Deon Fisher plays piano for 9NEWS

His piano playing speaks for itself. And the comments from 9NEWS viewers about it overwhelmingly gush about his talent.

Fisher says he doesn’t care he plays on pianos that are out of tune and don’t have all their keys.

“It’s like as a kid, I did not have a lot of great stuff,” he said. “Maybe you have toys that are missing one arm. Use that arm as a graveyard toy, just use what you have. Use the things in your head to create.

“Create something else out of that missing key and build a new thing, instead of being like ‘oh, that key’s not there.’ I’m going to go around it and come back, just threading.

“You can do whatever you want to do with that missing key. It doesn’t matter.”