What people don't realize about the internet is the fact that people here are effectively in a different country with different social norms and values.
She may have known that, but not understood it. She probably had no idea how widespread that single action could (and did) spread. She was not stupid, she was ignorant, there is a difference.
If the police hadn't tracked her down, everything would have been fine, and she would have likely never found out. everything would be happy end. (I would assume, didn't want to watch the video).
I think everyone who is insulting the girl who died is being immature, the fact remains, she died. I give my condolences to her friends and family and will respect her memory by not making a big deal about it.