You clearly have not watched the entire video, or were just not listening carefully.
The chance was the chance because of the extreme power of benthic and crafted gear this tier. You basically could get 4 benthic pieces (better than mythic ilvl loot), and 3 crafted items (440 with socket). With all the farmed up titan residuum, at azashara many people have 2/3 mythic ilvl azerite pieces as well.
He said he hoped that blizzard anticipates the amount of effort wf guilds put in, so that the race isn't too short. Because the last time more powerful loot than hc gear was easily available the raid lasted a day.