Moving Stair Clip

I was creating a sort of pop-up stair system in a completely empty superflat world. I clipped through part of one of the top stairs whilst walking up; as the stairs retracted, I was pulled down. When pulled down, there were 2 options: get bumped around but be fine, or be pulled underground in a crawl and have x-ray vision. I don't know what causes which to occur, but the former seems significantly more common.

From what I've found, very specific timings were required, but could be achieved either by the repeater lengths or by moving into the stair as it moved up at the perfect time.

 Unfortunately, some of the screenshots taken were messy and did not do much to show what was happening, but I included them anyway.