will look into it.
yeah, i wouldn't exactly call that video counterproof as there is something wrong with para in that vid. it should never visually show 4 stacks of para, it should proc exactly when it hits 4
how it should be: https://gyazo.com/9dcced1eddf6bc7118f318f7db267ae0
retail bug: https://i.gyazo.com/59f38a5cebe247e6ca942ec57b172a0c.mp4
as you can see here, it procs soon as you hit 4.
best bet is that in your video it is a retail bug, just like you had many others.
https://db.pandawow.me/?spell=109248
"If targets move 0 yards from the arrow they are stunned for 5 sec (3 sec PvP) and will be immune to the effects of Binding Shot for 10 sec."
http://forum.pandawow.ru/showthread.php?t=237355&highlight=binding+shot
as you can see, binding shot should NOT restun, but it did in the video. just a typical retail bug, just like in your video.
although, i'll edit the report if proven otherwise. i just got linked this video from my friend halta and can't find anywhere else where it procs during stuns. even if you do find a video where it procs during stuns, i'm just not 100% sure if it's a bug or not if it should proc during stuns, but i will take the commentator's word for it over than some random footage that we have no clue about.
reason why is simply because of the binding shot bug.