Is bilibili a general video site like youtube over there? Or hacker-specific?

It's a good question because china does tend to operate that way in terms of it's microblogs (renren is a good place to find a job!). Youku is their main youtube, although even that's not right because it's sorta twitch meets netflix meets youtube. bilibili (b-station) is what I'd call "deviantart meets hackernews of video".