You can cast whilst moving still
i use it every time i use the 5 second garrison hearthstone.
I really had fun incorporating it into beta tonight. It's not really too OP but using it off CD during movement really was nice to stack with other raid-wide utility.
I think it is a good ability just poorly done. if it would instead allow you to switch to AoTF giving all raid members almost a "vehicle" bar that would give the option to choose when the caster wishes to use the ability, maintaining a 3 min cd that it would be much more effective and also give a little more security. if hunter dcs in a group they may miss the window. not all in all most likely of situations, but at the same time it still gives the players an extra button that is quite useful to use as and when they wish.
It has potential, 6 seconds could mean a lot during a fight where you need to get a heal off but avoid some mechanic.