How does these events work?

Hi again

A few days ago, I got a few examples from Marv, and today I tried to add one of them into my games. But there is one thing I dont get at all.

http://www.castles-of-britain.com/blocksexample.mfa

In this example, its just one detector for plenty of boxes. How can this one detector single handed make everything work? It specificly says that the boxes shall fall when Global Value B is 1, and when the Detector overlaps another object, the Global Value shall turn to 0. Yet, boxes continue to fall even if the Detector overlaps stuff. What kind of magic stuff is this?

Also, is it possible to "convert" this into ForEach loops? What should I replace stuff with? Reason for this is my previous game ran much smoother with ForEach loops instead of fastloops.

On every run through the fastloop, the detector CanMove is repositioned relative to the block with the ID matching the fastloop index - so this one detector is passed around between the objects, only going to an object when it's needed, and the method doesn't need a detector for every single block.

Im actually gonna work more with MMF before I try understand this event. But is it possible to make a similar action like this using the ForEach object? The stage Im on now, on my own, I would probably do something like Start ForEach loop for Box and then "On ForEach Loop for Box + X Box Overlapping Obstacle = Set Y pos to desired speed", which in my head would make the box fall until it overlaps an obstacle. But this not look very smooth as the box will most likely stop moving somewhere half on the floor, and half bellow inside the obstacle...

I tried to connect my gravity player movement, but it just didnt get the same result when I replaced my fastloops with the ForEach loops... The box simply doesnt stop falling, and I dont think I can stop this loop as Im usually having more boxes that require the loop to be active.