even pvp eirs need to stage so why can't they max moon barrier?
you can walk through the barrier while your opponent can't so it might have some interesting applications if you can corner your opponent (most likely with holy spirit).
In pvp, the only safe way to heal I think is to use it after you land spirit. But then you give up all the initiative you have.
As to the vid, I can't say I was impressed. Maybe I fought Zyris too much to realize skill spam isn't a winning strategy. And there were a couple of times where that eir landed her AA that could have turned into huge damage if she did the bind combo.