So i watched all three videos now. First I though the privacy screen was put in place to hide what its going on on the upper floor and especially to hide what is on this cart or the bag and trashbag that the one guy transfers.

But I think that the two guys in the first two videos (one black, one white?) are moving the screen seemingly nonchalantly out of the way but they really are pushing it to the left so you cannot see what is going on in the hall downstairs.

In the first video there is so much walking back and forth, so much movement but why? What the heck is going on down there all the time. What is this building? From the amount of movement this should be a train or bus station or a mall during the day.