It seems like SoundCloud is more like the Vimeo for audio. They provide free and paid versions just like Vimeo. I don't think I've seen the YouTube for audio yet.
I'm sorry but I don't see how reddit fits into this equation. It's laughable to compare the work that went into building Curiosity or Ubuntu with reddit.
Ah the Leaderboard ;) The idea is really simple. People who are frequent watchers get rewarded with points and they show up at the top of the Leaderboard.
Really cool, and awesome implementation. I'm really digging the smooth transition on the infinite scroll. Also, the design and UI much better than the default bootstrap I've slapped on my app.
I'm not very well-versed in this type of stuff but I want to ask you an honest question: Is creating an open-source alternative to a closed-source software considered theft?