Twitter is a known tire fire. When I was out in San Francisco everyone who worked at Twitter had a shell-shocked look and talked about the experience the same way they would if they'd just gone to use the restroom and found a dead body.
I don't know any specifics of Vine. I didn't get a whole lot of details of the internals of Twitter, it seemed to be the usual complaints about companies — "things get done for the wrong reasons", "sudden changes in direction", "bizarre politics", "only care about the money now" — but compressed into a much shorter time frame.
"the same way they would if they'd just gone to use the restroom and found a dead body."
If that restroom had been basically showing for weeks that it was going to have a dead body in it any time now. Would still be surprising, but I'd be somewhat braced for it.