I tried this last night on a heroic HoL run. Running through the part where the statues all come to life and periodically fear me, I used to spend a good amount of time collecting my guys up.

Last night, with staggered tremor totems down I had exactly the same behaviour as seen in the video - the fear appeared and then disappeared instantly. Every single time.

Ok, so it's not very scientific, but I'm sold on the idea that they do indeed "stack" again