For the record, in the olden days before cell phones, people still didn't do anything. They just sat there stunned, and maybe whispered to each other.
totally
twitter isn't to blame here.
http://en.wikipedia.org/wiki/Diffusion_of_responsibility
Also, I don't think that because there's a name for the phenomena means that these people should feel morally just for their actions. A lot of people probably thought that someone else was going to call the cops to help Kitty Genovese, but all it would have taken was ONE. Same with Bill Nye here.
Certainly Twitter itself is not to blame here, but a lot of the mindset of Twitter
is. Remember, these people didn't just sit there in stunned silence, they TWEETED about it. There is some form of spectator sport in that, and I would rather distance myself from it, before I see some indication of that in myself.