Meet Dave Days, 20, musician, videomaster, and a graduate of Downingtown East High School.

Days also happens to have the most subscribers - 1.5 million - of any musician on YouTube. That's right, more than Lady Gaga and Rihanna. YouTube says his vids have attracted about 288 million views. He's about to post his 100th, titled "It's Never Going to Stop." Guess not.

What does Days post on his YouTube channel? "Different types of music videos," he says, "covers, parodies, original songs, and sometimes just me talking into the camera." His Miley Cyrus videos, in which a cardboard Cyrus is exposed to various comic situations, caught the eye of her people, and soon Days found himself making a video, "My Last Song for Miley Cyrus," with the real Cyrus.

"It was surreal," he says. "A lot of people saw the video and were disappointed she wasn't cardboard."

Only a month after graduation, Days moved to L.A. to do his YouTube thing full time.

That's pretty gutsy for a young man, isn't it?

"A lot of my friends from YouTube were already out there," he said, "and I was already making enough money to pay the rent and expenses. So I went."

Days wouldn't disclose how much he's earning now.

But how does he make money?

"When I was 16, I became a YouTube partner," Days says. And therein hangs a tale.

Annie Baxter, spokeswoman for YouTube, says that when people begin to post videos frequently, they are either invited or can apply to become partners with the website.

"We'll start showing relevant ads on their pages, and we'll give the creator a majority of the ad revenue," she says. For example, on Days' channel, maybe you'll find ads for guitars or Miley Cyrus CDs.

YouTube has a top-secret algorithm for detecting frequency and topic of posts. That tells it when to send the invitation for partnership.