Originally Posted by Gonkish

They specifically made sure in retail beta that Multi-shot was not castable on the move. They didn't want Hunters kiting 3 or 4 things at once without extreme difficulty, I'd imagine. (Which is ironic if you consider the BT trash farming mayhem. Good times...)

So Multi-shot has a 0.5 second "cast" time. There's no casting bar, but you can't cast it on the run. There is, however, a very slight but noticeable delay in its firing, greater than what can be accounted for with lag. That's not to say that they can't make it castable on the run, they just won't and with good reason.