Even in the very video, he mentions how the +10 Infested affix spawns mobs that can walk through walls/closed doors in Manor and pull the entire instance.
Hell, something completely different - on the mission table, your followers had ilvl of 800+ or something. It has since been removed, but really - with such gear, they should be soloing the expansion instead of bringing paltry rewards
There's a ton of stuff that got fixed in the last month, more than any other expansion. And while we didn't have the "stuck for 5 days under the ground in Garrison" fiasco, the sheer amount of broken things shows that it simply wasn't ready for such an early release.